The best speaker you ever heard?

Very true. Don't forget they are always produced in small numbers by obscure manufacturers or by reclusive audio geniuses who are convinced everyone else has it wrong. They also "blow away" anything you attempt to compare it to. Same for amps ;)

Each system excelled in it's own way:

~ Martin Logan CLS IIa (modified)/ARC Classic 120 monoblocks, with Kinergetics SW-800 subs/Krell MDA-300 monoblocks.

~ Magneplanar Tympani IV/Pass Labs X350, with 2 Entec LF-20 subs.

~ JBL 4344 (modified)/Mesa Baron (2 in vertical bi-amp, modified).

~ Apogee Stage/Lazarus 200/200 with REL Stentor III sub.

Classic Audio Reproductions...
I don't know why, but they popped into my head first.
(I'm kind of a JBL/Altec fan, anyway)
IIRC, these speakers were a 3 or 4 way, 15" with compression driver(s) I heard them at CES in 2001 with Atma-Sphere amps, the other gear is unknown, thpough the source gear was analog. So liquid, so wet, so palpable, so 3D. I spent over an hour in that booth, and spent mere seconds in hundreds of others that day. I was transfixed, and etched Atma-Sphere in my brain, as my JBL 4343 are so, so simular to those C.A.R. speakers. Maybe they were based on them?

Another runner up for me is the "big" Hales (remember Paul Hales?) with BAT SS gear in a large booth-room at HiFi'98 in Los Angeles. Superb!

Gershman Acoustics Opera Sauvage. At 2003 CES my wife and I heard the most incredible sound coming out of a little room at Alexis Park. It was the Opera Sauvage powered by Kora electronics playing Scherezade cut off the Burmester demo CD. It was the cleanest, most dynamic, and realistic sound I had ever heard. The closest I had ever heard to live music.

Radford 360 degree things playing Dark Side of the Moog V by Pete,Klaus and Bill. Heavenly! Happy New Year from England!