Far Cry 2, unless I'm very mistaken, is a typical FPS. Dragon Age: Origins is a medieval fantasy RPG. If you like RPGs, get Dragon Age. If you like FPSes, get Far Cry 2. The two are so far removed from one another that getting the type of game you don't like will be sheer misery for you. Whichever type of game you like, get it.
Personally, I prefer RPGs to FPSes anyday. I have played the hell out of Dragon Age: Origins and loved every minute of it. Bioware rocks!!!
Personal experience; common sense.