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

+1 for Sanders being underrated. My model 10e system with (2) Magtech stereo amps and LMS (loudspeaker management system) produces some of the most lifelike music I've heard and plays quite loud (unusual for 'stats).

I'm showing my age but those vintage JBL L100 speakers that so many people raved about in the 70's and 80's sounded just awful. A couple friends had them, one of them had a 4 channel quad system, and they were so proud. "Don't these sound great?!" "Uhhhh......"

On the modern end I have heard 4 different models of Wilsons at two audio shows. I just don't get it. They sound like fingernails on a chalkboard to me. The best sounding of the 4 were the smallest pair, Sashas I think. I can safely say that it wasn't the room because next door to the worst sounding demo (Alexandrias I believe) was an identical room with Sonus Faber Aidas that sounded gorgeous. Please note - I'm not saying that the speakers are bad (OK, maybe overrated) but Wilson must be targeting a particular kind of listener that craves microscopic detail over everything else. In one sense I have to give them credit for taking the characteristic of detail resolution to its logical extreme.

I think that ATC speakers whether passive or active are simply too honest to be ever considered overrated.

Way under rated 

Wilson Benesch
ProAc's
Chapman Audio 

Over rated.....to many to name...

For the money, a pair of 300 dollar Elac UB5 is hard to beat.  Sure, it's not a high end speaker, but for 300 bucks it is a damn good speaker.   The difference in sound between that and other more expensive speakers can be minimal.