Reel-to-Reel Player--Best Playback Deck 4-trk Stereo-Dependable, Easy Repair, Sounds Great

Top three 4-track capable deck almost at the pro level would be:

Technics RS-1500 series
Otari MX-5050 B-II
Revox B-77

and a bonus
Pioneer RT-1020L

These you would have to hunt locally for....they usually go over your budget online. Otari, pops up often locally and is a beast. I've personally owned all four of these models and a few others. Wondering why you are set on the 4-track format when 2-track is clearly superior.

Teac 3340S. Mine is 45 years old, restored 5 years ago. Sat for awhile and had to open it up to free up a couple relays but an excellent deck.  Spent a Saturday recording vinyl and the same song streamed to compare. Interesting results - fun day.

My Technics 1506 fall under most of your criteria. 

1. Magnecord 1024: USA built; three (oversized) motors; separate power supplies for transport and preamp; all discrete (transistorized) circuitry (NO early-gen noisy ICs or opamps mid-70s-onward Japan decks were crammed with to economize on board space at the compromise of sound).  Was the $800 alternative to a $2500 Ampex broadcast-grade machine in the 60s and 70s.  Even better than Revox 77 series (closest solid state equal in tone to a tube Revox G36, though).  "Under-the-radar" due to the name fading from history (which had been established in 1946).

2. Teac 2300/3300/6100

3. Pioneer 701 (or 707)/1020


I, personally, don't like auto reverse because it wears the heads out faster and drags any shed oxide back onto the tape (and, because: the more complicated logic/relay-controlled transports are the more at risk to fail).  I don't think, either, a 10 1/2"-reel machine matters IF unless the deck has 15ips as well as an optional 2-track pb head.

Also, again, the stock preamp designs of the bells-and-whistles-laden Japan decks tended to sound worse after a certain period (1973-); by the implementing of chips over separate transistors.  There is no more an overrated deck than the Pioneer 909 from 1979-1984.  All looks and no liveliness.  Endless maze of circuitry consisting of four preamps (rec/play FOR EACH DIRECTION) needing alignments; underpowered DC motors; and knockoff Teac-like heads supplied by the source which had been providing them for Dokorder(!).

teac 4300 is a good option too, if gone through.

keep in mind all of these decks will need service to varying degrees. Most will need a complete recap, so service can cost more than your purchase price on the deck.

I would look for a deck with really clean cosmetics and low wear (look at the wear pattern on the heads and tape guides for a clue).

Pioneer rt707 that has been totally restored, all new and upgraded caps.

Looks gorgeous, sounds even better.
Only one output but cannot have everything... Lol.

I sold TEAC many many moons ago and I believe the A2300S was their least expensive reel to reel deck.   I had the next model up which was the A3300S.  The Revox A77 was the best I heard at the time.  My brother had a Pioneer rack mount reel to reel which sounded pretty amazing.  I would make sure any deck I bought would be able to get serviced and parts are still available.  There is a company (can’t remember their name) that totally repairs and modify’s the different decks.  I would talk with them first and see what they say.  

Here’s a good article (link below). I always had good luck with AKAI’s back in the day (I owned 2). However, the Pioneer models (and possibly TEAC/TASCAM) probably has the most parts, etc available at good prices. I will probably be looking for a unit myself in the next couple of years (I have tons of R2R’s recorded off LP’s, fm radio-concert specials, King Biscuit, etc from back when I was younger). I’ll probably go to a reputable dealer who carries used and look for one that has been serviced. One thing about semi pro models is wear and tear. If the model was actually used in a studio or band situation, the unit may have been used many hours on a daily basis in a not so optimal room (smoke, etc). Many small studios do not service or maintain their equipment like the big one’s did.


https://hometheaterhifi.com/editorial/purchase-open-reel-tape-deck-one/

Pioneer RT-909 & Pioneer RT-707. I have owned both, they sound great and built like tanks.