The only problem I ever had with my 360 is that sometimes the drivebay sticks, while annoying it doesn't mean I have to wait to get a refurbished one.
If your into Japanese RPGs Playstation will have more of them, if your into games like Morrowind Xbox has quite a few of those. FABLE 2 looks awesome, KOTOR is a great game and Mass Effect looks awesome (same people who made KOTOR I).
It also has great action games and shooter games. IMO you can't go wrong with the 360, you get 90% of all the big titles with it like: Resident Evil 5, GTA IV, Stranglehold, Assassin's Creed, Bioshock (IGN gave the 360 version a 9.7), Soulcalibur IV, Guitar Hero III, Halo 3, Halo Wars, Madden, and a whole bunch more.
Since I'm not into much Japanese RPGs or fighters the only game I want for PS3 is MGS4, that's not to say the PS3 won't have some of the same big titles. Although I've heard Madden 08 for the PS3 has some FPS issues.
IGN: Madden NFL 08 Review
They gave the PS3 version a 7.7 and the 360 version a 8.7; to me it sounds like the 360 is much easier to develop for, wither your porting it or making changes to each version.
While LIVE gold costs money, like they say, you get what you pay for. Xbox LIVE totally destroys the PSN in all cases except PSN is free, but LIVE is totally worth it. You can even make free gold accounts but they expire after a month so technically you can play for free, but your achievement points won't last by doing so (nor your friends list), but at least you can try it out before you subscribe.
Killzone 2 is going to be mediocre at best, just like the first one (which I actually think was sub-mediocre. Halo killer my ***. Halo's story is much better/interesting than many shooters including Killzone. If you don't like it you:
1) Are biased against Halo and/or Xbox
2) Biased against Halo and/or Xbox but you are in denial about it.
3) You don't like Sci-Fi stories
4) You don't know what a good Sci-Fi story is about.