How are there people out there who believe GT5 is coming out this year??? Sony hasn't said a damn thing about even a release WINDOW let alone a release month or date. It's not coming. You'd be better off comparing GT to Madden '11, Halo Reach, FFXIII.
To answer the question, I pick Resort. Wii+Sports=MASSIVE
My Top 5:
Shadow of the Colossus, Metal Gear Solid 3, Shenmue, Skies of Arcadia, Chrono Trigger
My 2 nex-gen systems: PS3 
and Wii 
Prediction Aug '08: We see the PSP2 released fall '09. Graphically, it's basically the same as the current system. UMD drive ditched and replaced by 4-8gb on board flash memory. Other upgrades: 2nd analog nub, touchscreen, blutooth, motion sensor. Design: Flip-style or slider. Size: Think Iphone. Cost: $199. Will be profitable on day 1.
