I own both systems (As well as a Wii and a gaming PC... and a couple handhelds), and this is how I break it down, and keep in mind, some of this will be opinion, not fact, I will also be disregarding the community of each in my breakdown, but I will say here that in my personal experience, the online community on the PSN is slightly more mature... I.E. less kids screaming in my ear. I'm also leaving out the system's capabilities, because for the most part, neither system really out does the other consistently:
+ More exclusives/larger variety of game types
+ Free online multiplayer with the option to get premium services beyond that
+ Less prone to breakage (RROD anyone? I'm on my 5th xbox... 1st PS3)
+ Built in Wireless
+ Built in Blu-ray player
+ PSN charges you what the download you're buying is worth instead of forcing you to buy extra "points" to download something.
- No detachable harddrive
- Controller is a little outdated and uncomfortable
- PSN (Playstation Network) more prone to downtime
- A lot of "sleeper hits" that can be difficult to get your hands on
+ Detachable Harddrive, allowing you to bring your saves over to a friends place without having to bring the console
+ More stable online service
+ More comfortable controllers
+ Much faster updates to both games and system
- Forced to pay subscription for online play and other game services
- Console poorly built, more prone to break down
- Less game variety/exclusives
- Forced to buy ridiculously overpriced adapter should you want wireless
- No Blu-Ray
- Forced to buy more points than you need to buy games/content (I.E. X Game costs 560 MS Points, 1000 points is the lowest amount available that will allow you to buy it unless you have points left over from a previous transaction)
And there's no doubt more that I'm forgetting for each... but there it is. The above pretty well explains my experience with both systems. And just as a disclaimer, I owned a 360 long before I ever bought a PS3, and by no means do I go all fanboy over one system or the other...
However... In my personal opinion, the PS3 is the over all better deal. I do still use my 360 a fair bit (Mostly for Forza), but I've found a lot more that caters to my personal preferences in the PS3, both in games and online services, all other points aside.
All that said, again, this is my experience with the two systems, which happens to be in favor of the PS3. But it's really up to you to make the final decision.
It's hard to say from your choice of examples as for games you enjoy as most of those are on both systems in one form or another, and the wide range of genres can be satisfied by either system as well. Although I will admit the 360 seems more focused on the action/FPS crowd than anything else. Whereas the PS3 has a bit of everything, and has a lot more unique, original games (For better or worse) but isn't necessarily focused on any one area. Not to the extent that the 360 is anyways.