Why is 5.0 tier not in the poll? I find it one of the best ones ever, especially with MV (fights that can be fun to tank, not a lot of trash, Elegon), I'm sure some people would pick this one.
But for me, Ulduar is still the best raid. ToT is an awesome place, and a close second, but the trash (very fun to play with and intense, but simply too much) and way too many add fights kinda lower the score. Plus, ToT is as linear as a raid can get - Ulduar was an open place, you went where you wanted to.