XBOX 360 or PS3 ?
If I really HAD to choose, then PS3. The only things I miss are Hironobu Sakaguchi's games, maybe MGS and super street fighter 4 (seems like the arcade version is coming to pc though).
Not nearly enough to abandon my relentless PC elitism if you ask me. :)
Especially not when I've got both a SNES and MegaDrive (genesis for americans I believe) to satisfy my console needs.