I voted Revolution for now, but that could change in the future depending on a few things some others have already posted:
1. It really depends on where this format war ends up - if Blu-Ray indeed pulls through, a PS3 would be a great way to have a Blu-Ray player from the get-go, similar to using the PS2 as a DVD player way back when (I used it for both, as I didn't have a DVD player before buying my PS2). The possibilities of Blu-Ray discs holding games seems interesting, although I've heard from a number of people that only movies would be used, and games would simply be DVD9 or equivalent?
2. The Revolution really has me excited in the same ways the DS did. Nintendo seems to have struck gold with their DS, and the Revolution seems like a pretty cool idea if put into practice well. The games will determine whether the Revolution will soar or crash and burn, as it doesn't really offer much else...Gamecube was a bit of a disappoint for me (especially coming from some great titles on the N64) and I hope Nintendo can really WOW me this time around.
3. The pricing is obviously a huge concern of mine as well as many others...if Nintendo pulls off a cool little machine with more than half the price tag of it's competitors, it's safe to say I will certainly be picking up a Rev on the release date. If rumors of the PS2 being $500+ are true, well then I'm going to sit out for a year or so until I really see something that makes me want to throw down that kind of cash, like Metal Gear Solid 4, assuming it's as great as most of us expect.