What are some of the most underrated and overrated loudspeakers you’ve auditioned?

I always thought that the 15 ohm LS3/5A was way overrated. Same for the original Quad ESL. I know, that goes against HiFi canon but I've had both for extended periods, years actually, and they just didn't do it.

Underrated, well the Acoustat 2+2 was marvelous. Too big and heavy to keep but easy to drive and great to listen to. They seem to make nobody's list.

I'm just getting into the audiophile rabbit hole but so far PSB Imagine X2Ts have been the best I've purchased so far.

I never hear anything about them except for the occasional reviews which are always good which leads me to conclude that PSBs are underrated 

The best I’ve ever heard...and i’ve heard a lot, was a $2,000 pair of AudioNote speakers.  I think the ANe model.  This was set up in Tyson’s Corner (DC area) in a place called Deja Vus audio.  I believe he rebuilds older amps but could be mistaken about that.  Anyway, I can’t honestly say these speakers were better than any others, fiat there was some nasalness, if thats a word, and a small amount of breakup that some would fault.  They were connected to a $100,000 Audio Note amp which I’m sure provided most of the magic.  But the sound was glorious.  Never heard anything closer to live than I did that day.  Vu ( the store owner) was gently proving me wrong in my opinion of speakers being the most important part of the audio chain.  He succeeded with this demo.

i agree with everyone else that the biggest disappointment I have ever heard is McIntosh speakers.  I would add to that list Bang and Olfsun. Granted they are more of a (life style) speaker, but I really wanted to love their Omnipolars.  The MBL’s are simply amazing at creating a soundstage regardless of where you are in the listening room (the whole room is the sweet spot). I was hoping the B and Os would come close for much cheaper, but was hugely disappointed.  

Of course, I’m sure some people love McIntosh and B&O, they are just not for me.

Over-rated -
Avalons - Flat, Boring, makes all music sound homogenous
Martin Logan - I really want to like them, but the sound on more complex music always loses it's cohesion

Under-rated -
Dunlavy (RIP) - people always focused on "cheap parts"The Living Voice - Amazingly fluid

Most underrated Klipsch RP-260f without a doubt.