Well, look at the exclusives and decide.
If you don't have a HDTV then it really doesn't matter which console you choose in terms of picture quality (and even now they are pretty close).
Blu-ray players are cheap now, so thats not a huge issue.
Free online vs. $38.98 for 13 months...you will most likely have more friends on XBL...but that doesn't matter if you like to play single player games.