What Kevin44 said was one of the most common, shallow responses I get in these kind of situations. The reason most people get a 360 is because their friends have it and its more popular, the PS3 can break just as easily as a 360, the PS3 comes with a harddrive and a wireless controller on it's most basic form (40 GB) which is totally unlike the basic 360. The PS3 has Sixaxis (Which isn't a big deal but is pretty fun). BlueTooth is compatible with it, the internet is free, it is constantly being updated, it has Metal Gear Solid 4/Metal Gear Online,etc..While on the other hand: the 360 has a few more good games, more extra stuff you can pay for, more people play on it due to it's popularity and easier connectivity after paying for it, it has achievements, it has avatars, and it has Fable 2.
My best friend has a 360 and the HDD, etc...but unless I was to be jam-packed with tons of games, I prefer my PS3: a lot of my PS3 time is spent just messing around with the console, watching my vids, listening to my music, and looking at my photo albums. I also like the Blu-Ray.