I voted for CKII, but honestly I love X-Com as well (and hope that it wins, as I'm not super-hopeful CKII can pull it off).
A little annoying that Civ's expansion makes the list. Nothing against Civ, I've had oodles of fun with the Civ games (sigh... just wish the Colonization side games were a little deeper, always had a blast colonizing the new world with a modded in Russia), but its expansion shouldn't be held as "strategy game of the year". Expansion of the year nomination? Coo. But let the actual, full games have the awards.
Still, X-Com and CKII in the same year... it was truly a great year to be a gamer. Hey, and TEW 2013 is out next week, just in time for winter break!