Well, as a FF fan I would have said go PS3, but now its on 360 too it levels the playing field. Well, sort of. The 360 version is going to be a port of the PS3 version (meaning its being made for the PS3 and then copied so it works on 360) and while they say they are going to condense everything so the xbox version has just as good graphics as the PS3 version, this might not be the case.
Also the 360 takes HD dvds, PS3 takes Blurays. Blurays have more storage space so the whole game will fit on one or two disks, on the 360 version you will probably have to keep swapping discs. Also Bluray has won the format war on what is going to replace dvds, and HD dvd lost. This means that most films in the future will be on Bluray, so if you buy films now, and want to carry on buying films in the future, it would be best to get a Bluray player, which you get built into a PS3 but not the 360.
There is also a new Tomb Raider game coming out, but it will be out for both PS3 and 360, so that doesnt really help there. I think you'll find alot of games are being released for both consoles, because developing games for this generation of consoles in expensive so companies try to get as much money back as possible.
I think what it comes down to is what you want out of the you console. If you buy alot of films, buy a PS3. The 360 has a wider range of games, and if you had one it also means you could borrow games off your brother. But alternatively if you got a PS3 it would mean you would have a 360 AND a PS3 in your family, and there would be no game you couldnt get!
And yes the PS3 is bulky lol, but it looks FAR better than the 360 :P
EDIT:
OH and also, the PS3 has an rpg coming out called White Knight Chronicles http://www.jp.playstation.com/scej/title/shirokishi/
Watch the trailer, its kick-***.
P.P.S I keep thinking of things! 360s break all the freaking time, just like Windows (good ol' microsoft selling products that dont work properly), also I dont know if you like to play games online, but to play online on a 360 you have to pay, PS3 it's free.