Honestly it all depends on personal taste. If you invest a lot in a gaming rig, the PS3 may seem like the more attractive offering given the quantity of its exclusives. If you have a laptop like me, the Xbox 360 seems more appealing given all those console exclusives in addition to the true exclusives.
It's worth noting that I bought an Xbox 360 before the PS3 Slim came out. If I didn't buy an Xbox pre-PS3 Slim, I might have considered getting the PS3 first (instead of getting it last summer) given that it's got better value for money now with free online, wi-fi (no longer an advantage since the 360 S Model has it now), Blu-Ray, a lot of exclusives, etc.
That said, I haven't played the PS3 exclusive library enough to really say whether the PS3 exclusives are appealing. I did not like God of War III. I never was a Kratos fan and I just didn't like the gameplay personally. That's just me. I loved Heavy Rain (hopefully I'll love Indigo Prophecy/Fahrenheit too). Game sold a hell of a lot less than God of War but Heavy Rain is much more my thing. White Knight Chronicles was good but it was just that, good (or at least thats how it is with the singleplayer anyway. Multiplayer seems like its a different story). When I play a truly great RPG like Persona 3 that really sucks me in, there's no comparison. Didn't care for Disgaea 3 (maybe I'm just not used to this kind of game. I liked FFT and Shining Force but just because I like a couple SRPGs doesn't mean you like em all. Disgaea for whatever reason failed to hold my attention) and I got bored of 3D Dot Game Heroes after going through a few temples. I have LittleBigPlanet GOTY, Ratchet & Clank: Tools of Destruction and Resistance 2 all still sealed (first two bundled with the 250 GB PS3 I bought, the last was bundled with a Dualshock 3 controller).
I pretty much skipped last gen so I'm not really much of a Playstation guy anymore. My favorite games on the PS1 were RPGs (I'm not into the genre as much as I used to be though. Some of them are downright addictive for me but many of them these days make me go meh), sports games and MGS1 (but I haven't played MGS 2 and 3 yet).
Also I can't say much about PSN really. I played Super Street Fighter IV on PSN and I didn't run into problems. That's about it. When my Xbox Live Gold expires in February, I'm going to give PSN a real shake and see if my experience with it is positive overall like it was with SSFIV.