Reliability: PS3. Everyone knows someone that had issues with a 360.
Exclusives: It's all down to preference. However I'd lean towards the Playstaion for games such as Ratchet and Clank, ModNation Racers, Gran Turismo 5... The 360 also has games that I am really interested in such as Mass Effect (ME2 is coming to PS3 next year), Halo, Forza...
It should also be noted that the 360 tends to get exclusive DLC and DLC earlier than the PS3 eg. GTA, Fallout, CoD.
Online: 360. "You get what you pay for" applies here. Also what consoles your friends have will be a huge factor.
Cost: The 360 is cheaper than the PS3. However, if you add a years subscription to XBLA the cost is virtually the same. Games are also the same price for each console.
Controller: What you use to play the game is very important. However this is all down to personal preference.
Visual and Audio: For watching movies the PS3 wins this hands down. Especially in the audio department, it's an audiophile's dream.
In game visuals are more or less the same on both consoles, this really shouldn't affect your choice of console. Some games on the 360 look better than their PS3 counterparts and vice versa.
Whichever console you chose you will have a blast.