Because there are no games the Playstation 3 has that I want.
I play RPGs - both J and W, and wanted a system that had them. Therefore I got a X360 on launch day, knowing MS had to secure JRPGs to have any sort of marketshare this gen, and I was 100% right.
And thus far, I couldn't be happier with my purchase. If I was a PS3 owner, I'd be a trainwreck since I would have thrown $400+ away.
Back from the dead, I'm afraid.