The best speaker you ever heard?

For overall coherence, depth of field, width of image, and all round eveness from bass to the top of treble, I was most impressed with Avalon Eidelons driven by Conrad Johnson ART2 and Premier.
For the life like feel and presence look no further than Yamaha NS1000M's - Ebens sound similar, so do the John Marten design coltranes - but the Yams are easier to drive, adjustable, and just take you to the acoustic. Also they are still affordable.
I did hear some electrostatics recently by a Chinese company called King Audio - they were superb - probably good value for money too.
Art audio speakers have a sense of rightness, and cut from the same cloth, but more to the professional monitor side are Proac speakers - in a small room Response 1SC's are magic.
Before you spen any money though consider building them for yourself - I have my NS1000M's and my own handbuilt pair. And I do say that they are quite a pair indeed - (As the actor said to the bishop).

Lohan

update...best I've heard is the Magico five way hybrid speakers which require external crossovers and ten channels of amplification. Four 3 Dimension Audio SET and one push/pull (on the 86db woofer) 300b interstage coupled amp with custom tubed active crossovers powered the speakers.

Simply the best and the closest to the type of sound I have heard so many times at the Greek Theatre in Berkeley.

They do require a bit of saving for, though.......

Magnepan 20.1 and Quad ESL 63 seemed to provide the best reproduction of the human voice and reproduce acoustic instruments to my taste better than anything else I have heard. They arn't strong in bass but a sub can be used if you need to go deep into low frequencies.

I heard a pair of Analysis Audio Epsilons with all Electrocompaniet electronics,Soundstring cables that pulled me into the music like nothing else ive heard!!!I truly understand why fans of planar/ribbon speakers are such a devoted lot!!!

I recently heard the Montana WAS speakers which IMO are among the very best I have ever heard. Palpable soundstage and imaging, the lowest and best bass I have ever heard and absolutely lovely midrange and upper frequencies. Frankly, it is hard to imagine any speaker getting much better than this. I felt like I could walk up and touch the players on stage. Just amazing. If only I had the room to accomodate them!