Evil Smurf said:
Is this another chance to say Bastion is $20 on steam and Saints Row 3 + DLC is $40. Play Bastion, the SR3
This, Bastion is hands down the best indie game I've played, and one of the best games overall as well. Dat narrator. Haven't played SR3 yet though, but if you want to play that, get the Humble THQ Bundle instead.
From your list though, the DLC for Gears 3 is pretty fun, although there's not much single-player content to beat. The additions to multi-player are fun though, and the single-player missions from the General Raam DLC are good fun.
Both Fallout games are great, but if you lose yourself easily in RPGs, they are also massive timesinks. Same for Dragon Age and The Witcher, fantastic games, but easy to spend a LOT of time in. Haven't played it yet, but from what I've heard, I'd say go for Dishonored.