Each system has it's own merits. It really depends on where your preferences lie.
Personally, I would recommend the Xbox 360. Xbox Live by itself is almost enough to recommend it, particularly with the excellent Arcade offerings, such as Carcassone and Catan. The PS3 has some excellent exclusives coming, but the 360 has some excellent exclusives now. Bioshock, for example (of which the demo just appeared on XBL yesterday, and which all 360 players should get, not just because it's an awesome game, but because ENWorlders worked on it).
I have the Wii/360 combo, and while there are a couple of games coming to the PS3 that look good, they're not enough to justify the price to me. My wife and I play Carcasonne on the 360 virtually every day, and there are other games in that vein. I don't think you'd go horribly wrong with the PS3, but the games that I'm most interested in are either multi-platform (Rock Band or Assassin's Creed, for example) or exclusive to the Wii or 360 (Metroid Prime 3, BioShock, Mass Effect, Super Mario Galaxy, etc.)
That, coupled with my lack of faith in Sony's ability to course correct quickly enough means I'd go with the 360. There certainly are some good games coming for the PS3, depending on your preferences (Folklore, Metal Gear Solid 4, Uncharted: Drake's Fortune, Ratchet & Clank Future, Lair and a few others). But I'm not comfortable recommending Sony, especially with their current shell game of console pricing that's in play right now.