The best speaker you ever heard?

In my opinion, the speaker is by far the most important part of the audio system. After all, it is the only part you hear. OK, the other stuff really matters a lot, but without a great speaker... No go.

I am a bit 'speaker-obsessed' I guess, and now I am wondering: What are the best speakers you have ever heard, and what made them the best?
For many years I owned Crosby modified 63's with two pairs of Entec LF 40 subs. The sound was in many ways as good as it gets, particularly with respect to low level detail and dynamics at the soft end of the scale. Sadly, the speakers did have some limitations, dynamuc range at the loud end of the spectrum, bass extension without a sub, top end extension and most importantly reliability. Still one of my favorites. Note that Richard Lees is currently modifying the newer Quads and says that they surpass the 63's.
Revel ultima salon
Proac response D100
Quad 2905

stuck between the three for top contenders that I have heard.
Rockport Arrakis in a purposely built and tuned room mated with all Gryphon electronics (Mirage and Colosseum) is the best setup I've ever heard. I just can't imagine anything better, only different. The Clearaudio Statement turntable might have helped too.