Quick answer from me, as I have gave my views
here.
If you have had one 360 fail already, are you happy to get another, knowing there is a good chance that too will fail in the future?
Live is worth the cheap prices you can find it online, would be nice if it were free, but the performance you get from it (download speeds/streaming content without a hiccup) makes it value for money for me (only twenty quid’s worth of value for money though

).
PSN does not match Live if you like to play with a group of friends and have a private chat amongst yourselves, a lot of the games also cut chat off during loading, which isn’t a biggie, but the 360 doesn’t do that.
The flip side to PSN’s failure though, is that it seems to have a far lower number of idiots playing, whereas Live never seems to fail with bringing out the abusive spawn camping idiots, most of which sound like they haven’t even reached puberty. So from personal experience, PSN has a better class of player, or at least it did have a few months back!
Finally, the games are pretty much equal when multiplatform, there have been a few exceptions and these were apparently down to lazy programming on the PS3 port (Flashpoint looked pap on the PS3), but both consoles have exclusive titles, which is why I got both.
Whichever you pick, you’ll be happy.