Although there was an issue with the 360 at launch chances are you can get one that gives no problems.
I myself own one of the old 20GB 360s which has not even frozen since I got it in 2007.
I have friends who have been through several 360s as well as PS3s.
The newer models are more reliable from what I have heard and far quieter. As with all electronics however they can still fail but I wouldn't lose any sleep over that aspect.
I think both the 360 and PS3 in their current forms will provide years of trouble free gaming easily.
To be honest with you at the moment the PS3 has more exclusives on the horizon than the 360 (especially if Kinect is of no interest to you) but the 360 still has quite a stunning back catalogue of exclusives to catch up on.