shooter: GoW 2
rpg: Mass Effect
racer: Forza 2
sports: NHL 09
platformer: LBP

Oblivion
Fallout 3
Fable II
Enemy Territory: Quake Wars
Bioshock

Wii music
Wii fit
Wii mario kart
Wii play
Wii sports

Are the best, atleast to the majority of gamers this gen

Of games that have been released so far this gen these are probably the ones that are worth purchasing:

PS3

Grand Theft Auto IV (PS3 higher rated version but new dlc coming soon only to the 360 version.)

Metal Gear Solid 4

Valkyrie Chronicles

Little Big Planet

Uncharted

Ratchet and Clank Future

Resistance I & II

Heavenly Sword

Folklore

Prince of Persia

Warhawk

GT5 Prologue

Ninja Gaiden Sigma

Devil May Cry 4

Grid

Unreal Tournament 3

Mirror's Edge

Pixel Junk Eden

Pixel Junk Monsters

Calling All Cars

Wii

Mario Galaxy

Zelda: Twilight Princess

Super Smash Brothers

Metroid Prime 3

The World of Goo

Mario Kart Wii

Lost Winds

I know that with all I have for PS3 and 360 here people will say, "Oh, you're slighting the Wii!"  But, I'm really not.  There are a ton of classic games that you can purchase from Nintendo Channel's and download for the Wii, and if you would like to see them go look for them at http://wii.ign.com.  

360

Bioshock

The Orange Box

Halo 3

Gears of War I & II

Fable II

Call of Duty 4

Mass Effect

Oblivion

Fallout 3

Lost Odyssey

Braid

Pacman Championship Edition

Geometry Wars

Dead Rising

Lost Planet

Tomb Raider Underworld

Golden Axe:  Beast Rider

Assassin's Creed

Tales of Vesperia

Ninja Gaiden II

Sonic Unleashed

 The Crackdown

 Dark Sector

 Skate

Kameo:  Elements of Power

Banjo Nuts and Bolts

Viva Pinata 1 & 2

Some more Arcade games I haven't listed.

With all of these it must be a better gen than some folks think.