What's the best and/or favorite piece of equipment you've owned? And do you still own it?

Woodsong Garrard 301 wt Triplaner arm and Miyajima Shalabi cartridge. The beauty of it and the function always thrill me. Not to mention its drive and impact. Never had another TT that recreated music with such reality. And I just love to look at it doing its thing!

My favorite is a pair of horn-loaded 3-way speakers from the 1960s that were my Dads. University "Dean". They are huge and heavy and super-efficient (103 dB at 1 watt at 1 m). I have them at a vacation home and am always blown away by how great they sound. Big live, natural sound. You can feel the air movement when they are cranked. This system rivals my main system that costs 15 times as much. Unfortunately, I will have to sell them soon as we are downsizing, let me know if you are interested.

My biggest regret was selling a Sansui  777 integrated amplifier back in college. I have yet to see another one. 

Bought mint used Infinity IRS Beta’s over twenty years ago.  They are still mint and will never sell them unless someone wants to downsize from their IRS V’s.   Wish my hearing was improving, not declining.   

A Carver TFM-35 I bought NOS sealed in the original box from eBay in 2009. I still have it.

When hooked up to the Don Sachs preamp gives very little away to his Kootenay. I was surprised that it had very similar upper end resolution. It lost out in lower midrange resolution and bass.
Both things that could be resolved with some careful modification.

Also my Technics 1200G. First upper end component I ever bought. Total end game piece that I will probably never give up.

When I bought my first pair of high end speakers after graduating college. Year 1991 at the Listening Room in Scarsdale, NY. I listened to four different speakers all under $1,000 I think at the time -  Snell, Thiel, Mirage and Def Tech BP10. I remember the Def Techs cause i still have them in my basement storage room havent been used in a decade.  I was blown away by that bipolar signature sound at the time and that's when Def Tech's tower speakers were higher quality. 

My first decent speakers age 19, were AR2x. I was ransacked years later, took me a lot of years to get over the loss of those speakers.

I don't think I will ever part with my Emotive Audio Epifania preamp and Vita amps. I have owned them for over 15 years now (serial #2). Over the years some changes have been made. The original caps have been replaced with VH Audio copper teflon caps (preamp and amps). The preamp's original volume control was replaced with an autoformer volume control, and the plate voltage on the amps was increased to properly run 6550 tubes (originally used 6L6 tubes).
I've changed speakers a few times and am currently using Bache Audio Tribeca's. 

Original Audio Research D-150.

Wish I still had it!

Cheers!

Tice clock. Vpi magic brick. 
Seriously, As  smandlej above, Michell Gyrodec Full Plinth, SME V arm, remove the bridge, full Gert Pedersen mod takes it to another level. 

My all time favourite piece of kit is my Michell Gyrodec bought in 1992 (for £659 !!!) and subsequently upgraded to Orbe status. Now with SME V tonearm and Koetsu Black cartridge and still in regular use to-day. I have had other turntables down the years and wish I had had the funds to keep them rather than having to trade them in !! (Pioneer PL12D, Thorens 160 Super, and Dunlop Systemdek III, the latter equipped with an outboard power supply which made all the difference).

My favorite piece right now has to be a Lyra Kleos cartridge. I upgraded to a VPI Super Prime Scout but installed my old Ortofon cartridge. When I installed the Kleos, it didnt open the door to high definition sound it Kicked the door in with both feet. Couldn't be happier.

IMO, once you achieved a very high level of synergy (including your ears/brain) it's VERY difficult, maybe impossible, to pick one single item in one's setup. 
How tricky is it, to chose between Burmester speakers, Levinson CD, DAC, preamp and PassLabs power amp?!? 🥴 
Am I the only one here with such a difficulty in answering the OP's question? 
M. 🇿🇦 

My Aiwa AD F-770 three head cassette deck. 38 years and still going strong with nothing more than a belt change. Also, my Marantz st6000 tuner. These are the only things remaining from past systems.

B&K 202+ power amp.Still have it but it needs repair.

Probably my Totem Arro loudspeakers. Fantastic imaging, tone/timbre, and bass response especially for the size and price.  High Wife Acceptance Factor, too.  I still own them but am not using them now. They were a bit undersized for the room and for some complex arrangements (or high volumes). Oh, and the Wife Acceptance is no longer a Factor.

Garrard 401 TT w/Scheu Tacco arm and Dynavector Karat cart, driving JLTi MC phono pre (w/custom umbilical from the designer, RIP).

My Kyocera DA-610cx CD player. Purchased new in 1986. It's never needed service. It doesn't balk at playing newer file types like MP3's, FLAC's, etc. burned to CD-R's. The sound is warm and not overly bright.

Mark Levinson 23.5 amp and Magnepan 3.5R's.

I lost them when I lost my self to alcohol and the breakup of a relationship.  I fear they ended up in a dumpster.  Also my Lexicon MC-4 at the time and a dedicated HT in my own home.

I've lost lives, but sobriety is something no one can take away from me.

Tandberg 3012 integrated amp.  Original owner since 1983. Has never let me down. Still strong and loud.  Controls my B&W speakers with ease. Great amp.  

Infinity Rennasiance 90 spekers.  Got a pair of spare EMIT tweeters just in case.  That case has never come up.  Had a spare pair of speakers "just in case".  That case never came up either so I offed them.  

Pioneer SX-1050. Has more than enough power to drive any of the JBLs I have had. Has all the input and outputs one could need.

As soon as I get my Pioneer TT back the 1050 will go into my 70s disco system.

Adcom GFP-750 Class A preamp designed by Nelson Pass 

My Audiomodded Sony SCD333ES 5 disc SACD player/changer. Still makes lovely music to this day, going on 16 years now!  Absolutely terrific sound, and without any harshness associated with CD's.  Really shines with SACD's.

My powerfully powered
late model run 9/10 
Infinity IRS Beta speakers
Subwoofers and tweaks ?
Not likely !! 

Audible Illusion Modulus 3a preamp . Sold it .

First cartridge: NAD 9300, still have.

First receiver, Sherwood S9600 CP, still have.

Fist speakers, Polk RTA 12, still have.

First tape deck, Technics RM240X, still have.

Ive ADDED many components since 1981.

CEDAR DCX and CRX, invaluable in dubbing noisy old LPs. got 'em for a song on Ebay. one day i might spring for the DHX [dehisser]. 

On my best components I actually have two, one is a custom turntable made by Peter with PBN Audio and it sounds fantastic and it’s candy to the eyes.The other is a pass labs X A160.5 mono amps and I no longer own either of them I’m sad to say. My favorite piece is a recently acquired rel 812 sub and I am totally blown away by it, has excellent Impact without boom, spent a lot of time dialing it in but it was well worth it.

Original Snell Type J speakers. I listened to more great music on them than on any other piece of equipment...still have them, but let's say they're retired.

Rega Planar 8

I’ve had quite a bit of gear come and go but my Janszen zA2.1 have remained and will always. The best electrostatic sound in a WAF friendly package.

Krell ksa100. All original. Getting it recapped this week after 30yrs. Can’t wait. 

Pioneer pl-630tt with ortofon black mm cart. Still works and sounds great. 
Things sure were made well back then. 

The ‘68 Les Paul Custom I lost in a burglary during college....still hurts.

After that, I’d have to say the Thiel 3.6’s.  I down-sized years ago, but I had a lot of joy thanks to Thiel.

My favorite is my pair of Watkins Stereo WE-1s speakers, they are large but have such a sweet musical sound, even at 37 years old. 

The KLH Nine full-range electrostats I bought in 1991 from HiFi Classics in Far Rockaway, NY. $500 - and a major bargain! Still have them in occasional use along with the pair of Futterman H3aa OTL amps. 

For me it’s my Shindo Monbrison preamp.  I had discounted the importance of the preamp in my system before I got that one about 5 years ago, even though I had gone through some good ones.  
The Shindo just made everything sound better, full and rich and layered and textured and natural, with lots of detail, no matter what other components or music I throw at it (and I’ve changed a lot of components during the last 5 years). I doubt I’ll ever part with it, unless somehow I can afford to go further up the Shindo preamp chain, which would be quite expensive.  
And no, I’m not a believer that it has to be all Shindo or no Shindo.  It’s my only Shindo component (outside of some cabling), and I think at least at the preamp level it’s astoundingly good by itself, at least to my ears.  

My Apogee Duetta Signatures. Purchased in 1991. Still the centerpiece of my system.

Oops right in addition to the Ohm Walsh since 1982 there is my Linn Axis since 1986.

Lot's to choose from but probably my Nakamichi Dragon. I was a cassette deck-aholic! Next would be my 70lb Thorens TD125 Black Forest Edition with SME Series 3 tonearm and Shure cartridge. Currently I love my KEF R series speakers and SVS SB 3000! I'm now an HT junkie...

My Sonus Faber Electa Amator speakers. They are the original ones, bought new in the 1990's, with the marble/walnut stands. If I can pick two, it would be my Stax headphones (currently 009s).

Lafayette KT-550 tube power amp for one.  It was built in the 50s and still kicks the ass of most any amps I have ever heard even in stock form.  Other than that, the large Ohm Walsh I had in college playing dark side of the moon.  After that it is all the products I build.

Happy Listening.

Linn LP-12. It still makes music.

Original Rogers LS3/5a 15 ohm , purchased new in 1975.  Sold in mid 90s along with all my other equipment to raise cash to start a business.  Ted to see them go, but the business was the best decision I ever did.  I could buy them back, many times over, but, kind of like the high school sweetheart- reality probably not as good as the memories.

My Decware Rachel integrated. At low levels, that thing was sweet as hell. The midrange was to die for. I wish I had kept it instead of selling to upgrade. 

Oh yes MC, Joe Weber at Corner Audio. Spent lots of money there, Joe got me into high end audio.

Those were the days! Joe was one of the very best. He was great like that. Let you alone to listen. As good as his stuff was, you couldn't help but get hooked. 

In those days I would go to Portland a couple times a year. Must have visited every high end store along the five from Seattle to Portland. Wish I could remember the tube amp Joe had, and the rest of the system, it was superb. Absolutely superb. And people talk about the room, it was a cube! A freaking cube! Horrible dimensions! Yet he got wonderful sound. So there!
To get some idea how good his system was, my wife got dragged along (it was her family in Beaverton) and that first time we heard the Model 10 speakers on the drive home she asked me if we could buy them. They were $2500, and I had just spent $1700 on speakers not a year before. They were that good.

As much as I love listening to audio, when it comes to physical possessions I'm 'way more emotionally attached to my musical instruments and to my record collection. That being said, I guess I got to say that my favorite component is my PrimaLuna Integrated.  Not only does it give me lovely, immersive sound, when something gets noisy it's fun to turn it upside down, take off the bottom and squirt Deoxit on the offending knob.  The 'Luna is so wonderfully straightforward and un-tweaky.  Then again, I've suddenly developed an unmistakable yen to audition a Grandinote Shinai.

JansZen 410's

The Maplenoll Ariadne Signature TT i still own modded with extra arm and 100lb platter and custom motor. Regretfully it makes my large digital music collection sound uninspiring and has therefore decimated my choices  about 80%.

It is not my best component, but it’s my favorite component, largely out of nostalgia: My Thorens TD166 MKII turntable. I still own it and use it. I bought it (with my parents’ help) in 1977 or 1978, at Audio Consultants in Evanston, Illinois, while I was still in High School. After 15-20 years in storage, in 2018 I brought it back into the Audio Consultants shop, had it serviced and overhauled, and a new cartridge (an Ortofon 2M Bronze Verso) installed, and put it into service in my system. It was great to see the owner Simon, who sold me the turntable so many years ago, in the shop. While getting the turntable sorted, I also bought several new components from Audio Consultants to get a great 2-channel system up and running. Simon has since retired, and Audio Consultants is now closed, to my sadness and dismay (but happiness for Simon). This may not be a top of the line turntable, but it still sounds great. And, I was loyal to that shop for more than 40 years, having bought many things there over the years.