This is kinda for me, trying to see whats what. Scores are average listed on GameRankings from high to low.
DISC - Excluisive
Resistance: Fall of Man™ - (89%)
Ridge Racer™ 7 - (78%)
Full Auto™ 2: Battle Lines - (71%)
Genji™: Days of the Blade - (58%)
MotorStorm™ - (No reviews of western version)
Gundam – Target in Sight - (No reviews)
FORMULA ONE CHAMPIONSHIP EDITION - (No reviews)
DISC - Also on the 360
Call of Duty 3 - Activision UK Ltd - Disc
Marvel: Ultimate Alliance - Activision UK Ltd - Disc
Tony Hawk’s Project 8 - Activision UK Ltd - Disc
Sonic the Hedgehog™ - Sega®Europe Ltd - Disc
Virtua Fighter™ 5 - Sega®Europe Ltd - Disc
Virtua Tennis™ 3 - Sega®Europe Ltd - Disc
World Snooker Championship 2007 - Sega®Europe Ltd - Disc
NBA 2K7 - Take 2 International SA - Disc
NHL 2K7 - Take 2 International SA - Disc
Blazing Angels Squadrons of WWll - Ubisoft Entertainment SA - Disc
Enchanted Arms - Ubisoft Entertainment SA - Disc
Tom Clancy’s Splinter Cell: Double Agent - Ubisoft Entertainment SA - Disc
The Elder Scrolls lV: Oblivion - Ubisoft Entertainment SA - Disc
Def Jam: Icon - Electronic Arts Ltd - Disc
Fight Night Round 3 - Electronic Arts Ltd - Disc
NBA Street 4 Homecourt 2007 - Electronic Arts Ltd - Disc
Need for Speed Carbon - Electronic Arts Ltd - Disc
The Godfather: The Don’s Edition - Electronic Arts Ltd - Disc
Tiger Woods PGA Tour 2007 - Electronic Arts Ltd - Disc
Untold Legends: Dark Kingdom - Electronic Arts Ltd - Disc
F.E.A.R. Vivendi - Universal Games Intl SA - Disc
NETWORK
Tekken®: Dark Resurrection - SCEE - Network
Lemmings™ - SCEE - Network
Go! Sudoku - SCEE - Network
Go! Puzzle - SCEE - Network
Blast Factor™ - SCEE - Network
flOw™ - SCEE - Network
Super Rub’a'Dub - SCEE - Network
Gripshift - Sony Online Entertainment - Network
Kinda spoils the fun really. Yes loads of games are available at launch, but a fair chunk are already availalbe. Its one thing if they are out on the PC aswell, but another if they are out at a cheaper price on a cheaper console.
I think a lot hinges on Motostorm. Its fairly original for a racing game, and looks awesome. I'm sure its top of the list for many people.
The only other thing to consider, is what games are coming out on the 360 before the end of March. A quick check shows:
Crackdown
GRAW2
Forza 2
C&C3
Mass Effect
(Some of those are out the week after the PS3 but its still March and only a week

)