I also would pick Red Dead Redemption, so you aren't alone. Game was better than any GTA game to date IMO. Second would of been Mass Effect 2.
However, I think World of Warcraft is the real game of the decade winner. Half Life 2 was good, but WoW influenced a much larger audience. I no doubt had my fun with that game in the past.
No idea why Zelda Wind Waker or Batman is on that list. Quality titles, but not only do I feel that there are some more deserving, but I imagine a lot of people feel that way to the point I'm confused how they are on the list. If some of those games made the list, then why no Super Mario Galaxy?