I'm completely happy with the 360. The improvement over last gen has been massive in terms of game selection. I couldn't have cared less about the Xbox, but they've made a fan out of me this generation. XBLA is just the shit.
I feel I'd be lying by omission if I didn't say I kick myself sometimes for having shelled out $500 on the PS3. Especially when I look at the slew of 360-only/multiplatform games coming out in the next several months. I've gotten to spend woefully little time with it so far. On the other hand, PS2 backwards compatibility is a must have for me, and looking down the road to LittleBigPlanet, Valkyria Chronicles, inFamous, Heavy Rain, etc., I know I won't be ignoring it for much longer.
For all the ridiculous fanboyism it's brought out in people, the competition between the two has so far been nothing but a boon. I don't think I'd be nearly as happy a gamer if these two hubristic, assholish companies weren't constantly trying to one-up each other. I think the only area in which they haven't lived up to expectations has been sales.