I got a PS3 and am LOVING it.
I did a lot of research - games out right then, upcoming launches, etc. - before I bought my PS3. The reason I chose PS3 over the 360 was pretty simple.
The 360 has sports titles, FPS, Mass Effect, and... Uh... ?
The PS3 has a little bit of everything. As some one who doesn't care about FPS or sports games, that's a lot more appealing. It opened up with a jab of Ratchet & Clank, Motorstorm, Warhawk, Heavenly Sword, some Ninja Gaiden Sigma <which is technically an exclusive, but not really>, etc. Variety! The first nasty right hook was the REALLY good stuff that's coming up. LittleBig Planet. MGS4. Tekken 6. WarDevil. Devil May Cry 4. The 360 having no more good exclusives (that I've heard of) lined up. Then the free online...
Then the PS3 threw the 'backwards compatibility' (I didn't have a PS2) into the ring and TKO'd the 360.
In short:
360: Started off as the more solid console between the heavy weights. Sony made a few gigantic blunders at the beginning, and it really helped sell the 360.
Wii: Was the innocent lightweight that every one fawns over, but can't really deal with its 'real' competitors on technical aspects. A few gimmicks, a good marketing campaign, and BAM. Bajillions of them sold, mostly to people that aren't concerned with the fact that it's about as powerful as the PS2.
PS3: Like a charging rhinoceras, a slow rumbling start. It's starting to break into a gallop now, though, and soon it'll hit the full run - from there, it'll obliterate all its opposition. I've noticed things that used to ridicule the PS3 now worship it. And it hasn't even hit its full stride yet.