Best of 2010 - Best Expansion Pack Nominees
Find out GameSpot's nominees for Best Expansion Pack of 2010!
I'm not sure how fair is it to mix expansions and "stand alone expansions" - those are full games really, only making sure you'll not be mad cause they use the same engine than a previous game.
"Dawn of War II: Chaos Rising" for me, but that's just a personal preference. "DA: Origins" is more likely to be the popular choice for the award, though.