Which Steam Game Should I get (PC)?

I like all these games (list below). I won't to buy 1 or 2. Which is best. Also I have a good PC to run these. I'm buying from Steam.

Orcs Must Die 2
Torchlight 2
Batman Arkham City
Xcom: Enemy Unkown
Fallout 3 GOTY
Deus Ex Collection

Thx. I already have ALL Valve Games.
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