Currently Online 
If next gen begins the way this one ends, then probably not. I'm not a fan of Gears of War, which pretty much leaves Halo and a few downloadable games as my only reasons to buy a 360. Keep in mind that I'm about 50% or more a PC gamer, so a lot of console "exclusives" really aren't for me. In my opinion, this is more significant for Microsoft than for Sony. Also, I don't want to pay for Live, as I don't really care much for online multi-player, but the 360 is pretty much crippled in a lot ways without it. When it comes down to it, I just really like the variety and wider selection of exclusives associated with the PS3.
That's just guess work, though. If Microsoft wows me, or Sony disappoints, I could very well go with the 720 as my primary console. I did it when I switched from Nintendo to Playstation, after all. However, for that to happen, I think Microsoft would need to have more true exclusives and to add more value to Live.
Of course, if I'm making a lot of money by that time then this could all be moot, as I would probably buy both.
