I see a lot of you have mentioned B&W speakers. I would have to agree that some of the higher end stuff does indeed sound incredible. However I have to admit that the best sound I have ever heard from speakers of any kind that I have listened to so far have been some of the larger Martin Logan's, that have been set up properly, and have some high end electronics behind them.
However I went to a B&W shop in Sacramento a few weeks ago, and listened to some B&W 800 or 802's, I don't remember which, using meridian and classe' electronics, and really liked them, but found that I preferred the way my ML Mosaics at home on my Marantz SR5600 sounded. Though, the ML Summits with the Anthem Statement electronics on them at the other shop I've been to, when positioned properly, just blow away anything that I have ever heard. It's more than sound at that point, it's a feeling and it's like experiencing a phenomenon you have not experienced before. It's very different from regular boxed speakers, and a lot of fun.
Unfortunately for me, I have not really heard else other than Paradigm, Monitor Audio, and DefTech, which also really sound very good in their own rights. I've heard Bose too, and wondered how anyone could be swindled into thinking that they really sounded any good. I guess that they may sound better than some boomboxes from times past, and maybe some clock radio's, but in my opinion, not that much better.
I wish I had had a chance to hear some Magnepans, since I have heard some nice things about them, but I just haven't found any nearby yet that I can listen to.
-capT