System sellers??? Maybe Kinect, maybe Move and probably Gran Turismo 5.
Halo: Reach isn't the first Halo on 360... no system seller because Halo 3 was it... but Gran Turismo 5 is the first major GT for PS3... system seller confirmed (or maybe?).
Then I say "PS3".
But Move and Kinect are unknowns so...
Move sucess = PS3 wins
Kinect sucess = Xbox 360 wins
Move and Kinect sucess = PS3 wins (because GT5)