“What game to buy on Steam?” quandary.

So I’m looking at my Steam account (moe.lane, by the way; I understand that people can friend each other on that service, or something) and I’m seeing that LA Noire is being offered at 75% off ($12.49) and Batman: Arkham City is being offered at 50% off ($24.99).  I can manage to swing one of these; anybody got an opinion?  I like the noir genre, and I play action games; I’ve also heard people rave on and on about both of these.  Feedback?  The sale ends at about noon January 2nd.