The best speaker you ever heard?

This is not strictly a commercial system - one of our lecturers Sir Malcom Omar Hawksford at the University of Essex ran a couple of experimental systems which I still remember to this day. Heaven, and this was in 1988!
1. Digitally room equalised crossover with Audio Physics (Virgo ??).
2. Celestion 6000 system (600 with dedicated stand/'globe' subwoofer) with a digital crossover fed by a high end Sony CD transport and powered pair of Musical Fidelity A470 monster monoblocks.

For commercially available speakers, a few speakers stand out for me and all very different! Cabasse Atlantis, Quad ESL63, and Magnepan 20.

Infinity IRS Omega, the last of the fame.
Heavily upgraded (new Auricaps, coils, DH Labs cables etc...),
I own it and I think I may be the only on in the states with a pair, as it was only marketed in EU and Japan.

best or not it's depended on your mind and your ears?

Steve01s$, where did you get to hear them? I guess this is an instance where you really do not want to hear them, because once you have you are hooked. I have the LaCampenellas now and find them outstanding. Furthermore, at only 187 pounds each, they are manageable.

MBL 101-D's is by far the best. These were the best back in the 80's, and still the best today by leaps and bounds.