Okay, lets look at the libraries here, since most people have already touched on the consoles themselves. For one test, I found out how many GOOD E/E10 games there were for each system. Here were my results:
Viva Pinata (360)
Ratchet and Clank Future (PS3)
Really, those were the only ones I found. So lets move on to budget titles, where the 360 REALLY wins, thanks to a large back-catalog of underappreciated hits from the launch window. Seriously, what did the PS3 have at launch other than Resistance? Gundam? and even then, it was a whole YEAR after the 360 came out.