Which RPG series to buy for the Xbox 360?

I've at least played these games in demo/borrowed from friend but don't know which to buy.

Don't care about the price just wan't to know which is more enjoyable in your opinion.

Fable 2 and 3

Mass Effect 1 and 2

Dragon Age 1 and 2

Elder Scrolls 4, maybe 5 when it comes out

Final Fantasy XIII and XIII-2 when it comes outWhich RPG series to buy for the Xbox 360?
elder scrolls i've wasted 256+ hours on oblivion aloneWhich RPG series to buy for the Xbox 360?
Elder Scrolls 4!!! You will not regret it once!!! Hours and hours of fun!