If you mean best exclusves:
It just depends on your personal preference.
Sometimes exclusives go to other platforms too after some time.
Games that I like/think look good from both consoles:
Xbox 360: Halo, Gears Of War, Splinter Cell series, Forza.
Ps3: Uncharted, Grand Turismo, Infamous.
If you mean which has technically MORE exclusive 7th generation games (not necessarily better)
Maybe this link will help:http://en.wikipedia.org/wiki/List_of_video_games_exclusives_%28seventh_generation%29