Both have pros and cons its really a matter of taste but i made this little pro con table to give you the general idea.
Better hardware = Better graphics (depending on the game as well ofc)
More exclusive games. (games not available on other platforms)
Free Online play
Runs Bluray discs
No dedicated servers (one of the players are the hosts in basically every game except the MMO's)
Higher Price than Xbox 360
Less secure online experience (referring to all the succeeded attempts at hacking its system)
more games available than PS3
Easy communication with windows PC (streaming movies, data storage etc)
Kinect if you enjoy the whole motion gaming thing
Subscription fee for online gaming
A tad outdated hardware = Not as crisp graphics as on PS3
You will be able too find allot of your games on PC as well (not sure if its a con? Depends on how you feel about that)
Too you fellas saying "You can hack PS3 and skip paying for the games" That is possible for Xbox 360 as well. There is 2 reasons people do not do this to frequent on either of the consoles.
1) You loose the warranty which means if the console breaks: sucks too be you.
2) You get banned from online playing which sorta kills both of the consoles IMO even though i do enjoy SP-Games.
I'm a Xbox 360 owner but i have no intentions of bashing PS3. For me it was the price and the fact that my friends use Xbox. Its always more fun to play with friends right? ;)
Good luck with making your decision, whatever you choose i'm sure you will be pleased with your gaming experience.
Cheers // Unholee