The games you do want are games which the Xbox 360 is strongest in.
RPGs.
Mass Effect 1 (2 upcoming)
Fable 2 (3* Downloadable content)
Exclusive content + Fallout 3 plays better.
Risen (Upcoming)
Mahesty 2 (Upcoming and unique RPG)
Star Ocean IV
Magna Carta 2
Lost Odyssey
Blue Dragon
Venetica
+ Others are exclusive RPGs.
For shooters
Left 4 Dead (4 player coop Zombie shooter)
Gears of War 1/2 93/94 metacritic third person shooters.
Halo 3 (The best selling shooter of the generation)
Halo ODST (Expansion to the best selling shooter of the generation)
Tease.