Best piano version of Moonlight Sonata?

Kempff and Ashkenazy are both exceptional choices and would probably be my two safest recommendations. Gould was brilliant, but his style is polarizing and the re-edits he did on many of his recordings just drive me insane from an audio perspective. I'm embarassed to admit that they taint my enjoyment of some of his pieces.

Notable in its absence thus far is mention of Solomon... he is responsible for my favorite interpretation of this particular piece. Well, favorite at the moment ;) Still, brilliant.

Other votes from around here (work) are: Horowitz, & Richter

For the best Moonlight sonata, I'd recommend Emil Gilels on DG. Simply perfect. Radu Lupu also made an interesting Moonlight sonata recording on London's Weekend Classics label, marred only by the somewhat understated 3rd movement.

The one you play yourself on the piano in your den/livingroom. Seriously - who didn't learn Moonlight Sonata while taking piano lessons as a kid?

My favorite way to play this back then was as fast as possible. It's a whole different song that way. Damn, you could probably put drums to it and "rock-out" :-)

Enjoy,
Bob