What is the best solid state amplifier you have ever heard?

Interesting question in that I have not yet zeroed in on the amp that makes me want to stop looking.   I have owned all of the amps below so I had a long time to evaluate each.

The top 5 in no particular order would be;
Clayton M300 Class A monos
Lamm M1.2 Hybrid Class A monos
Cary CAD 500MB monos
McCormack DNA-500
McCormack SMc Audio DNA-2 LAE

Others that were ok to pretty good include;
Cary CAD 500.1 monos
Clayton M200 Class A 
Acoustic Imagery Atsah NC1200 monos

Hard to believe there's no mention of the ASR Emitter II Exclusive. It runs on a battery, fed by two power supplies. It's been a venerated amp since the 1980's.

If if you can find a threshold S/500 is a great option even when is from the 80’s it is a great sounding amp. 

Threshold S/450e

Levinson 23.5I use the amp to power Tympani 1-D's.Previously, I listened to a JBL Hartsfield / Marantz 8b combo daily for years.  When I purchased the 23.5, I swapped it for the 8b and was shocked to hear that it was just as warm and musical, but had even more bass control.  I've owned the 23.5 twice now... I lust for 20.6's!