I don't have a 360 (yet), and I don't buy that many games. Assuming money was not an issue, though:
360:
Halo 3
Gears of War (If I had a 360 earlier, otherwise I'd just take the GeoW2)
PS3:
MGS4 (I'll get around to it, still haven't played any MGS)
CoD4
GTA4 (bought by bro, but I don't play)
Resistance (see GTA4)
Assassin's Creed (bought by bro, but I wouldn't pay full price)
GH3 (would buy if I had more money, will instead wait for GH4 or RB)
Wii:
Wii Sports
Mario Kart Wii
SMG (friend has it, so won't bother buying since I'm cheap)
Wii Fit (will buy once it's in stores)
SSBB
Mario Party 8 (like GH3, will wait for the next one unless I were rich)
Zelda:TP (like SMG, friend had it)
That's 15 total, if I were rich and didn't have friends to borrow from (I may also check Oblivion out, but on the PC). My X360 and Wii library will have many more games that don't sell as well (JRPG's and third party Wii), while my PS3 library will see many more popular titles, some possibly new top 10 entrants (FFXIII, FFXIIIv, GT5, LBP, etc).
