The ones that made it into the top five for voting are : Avast!, Microsoft Security Essentials, Avira AntiVir, ESET Nod32 and AVG.
What did you vote for? I went with Avast! because that's what I've been using for a bit. Thinking of moving over to Microsoft Security Essentials, but not sure how much more powerful it is (haven't read much about it)
Avast! is much better than MSE, so I suggest you stick with Avast!. V. 5 of Avast! pretty much pwns all other AV's (at least it's latest beta version does IMO). I voted for Avast!. MSE is a good AV, but Avast is better, from personal experience.