The best speaker you ever heard?

Avantgarde Mezzo.
The basshorn will give you fast clean bass even at low listening levels.
Sound is absolutely the BEST I have ever heard.
Looks are stunning: my wife likes them, my and her friends also. So you can put them in the living room.
See what www.high-endaudio.com has to say about AG's.

Ridgestreet Audio Designs Sason LTD...perfectly coherent from ~high 30 Hz to the highest treble, deepest, most layered soundstage I've ever heard, image and tonal density beyond reproach, amazingly natural portrayal of detail...an extraordinarly expressive and communicative speaker! It doesn't go real low (2-way with 7" mid/woofer), but what it does, it does better than any other speaker I've heard. Never even missed the bottom 10 Hz. I've got my order in!!

The Avalon Eidolon Diamond with all Spectral components and over $20k of room treatment at Progressive Audio in Columbus, OH was able to soundstage and image almost as well as the Sason's, but tonally it was too lean. Substituting an ARC VT200 added a little weight to the lower midrange, but soundstaging and imaging suffered. It was a tweaked out system in a tweaked out room.

I've heard the MG20.1R's in good setups/rooms that were also very good, but I'd take the RidgeStreet Audio Sason's over anything I've heard in 20 years.

The word "best" covers a lot of ground. It has always been reserved for the Quad ESL-57, but... it is slowly becoming the Gallo Ref. 3.1 (which I have owned for a very short while). I will know for sure when the Edge M6m amp (another Audiogon purchase) gets here next week.
As long as my hiney graces the well worn seat in my recliner, the 3.1's are Nirvana. Only the 57's have given me the musical enjoyment that these funky looking Gallos have.

I have owned the following speakers in the last few years. Please keep in mind that I like everyone of them during the path of upgrade/changes with an exception of the Advangarde Duos ( I dont no what is so goog about them).

B&W Nautilus, 800
Avangarde, Duos.
Magnapan 20.1R and 3.6R
Wilson WP7 and Sophia
Martin Logan Prodigy
Kef 207
Usher Dancer 8571 and Be10
Revel Salon and Studio
Eggleston Anda II

I bought a pair of Black Swans from Gershman Acoustics a few weeks ago (do not mistake this for Swan speaker). This by far is my favorite pair of speakers in my 15 years as an audiophile. I am hoping to have enough time to post a review soon. I thought the speakers sounded good at the show, oh man, they sounded a lot better in my home. I am running them with some Conrad Johnson, Cary, and McCormack electronics (LP70s, CT5, UDP1, and Premier 350: Cary: SPL-05,CAD-805 AE, SACD306).

I have heard too many speakers to list. Basically I have heard pretty much everything or as many as a i could in the 4 days I spent at the CES each year, Alexis Park and Venetian (2000-2007). Some sounded really good other sounded like crap regardless of the price. If you are looking a pair of speakers in 20-30K range, please do yourself a favor and listen to the Black Swan. They are that good....Acurate, cohesive, expansive sound stage, (wide, deep and high), balanced from top to bottom, beautiful mids, and airy and silky smooth highs. (sound stage is not as deep as I would like to have- potential room acoustic isssues.

The best speakers I heard was at the MBL show room this year.

Without a doubt, Dynaudio Evidence Masters. Even in a smaller room they are oustanding. Low volume, high volume, any music you play, perfect.