Gerrard for me. The number of times he has saved Liverpool is amazing. Sure, he hasn't got the technical ability of Messi but he's more likely to take control of a game. Think back to the Champions League final against Milan. Gerrard pretty much took that game by the scuff off the neck in the second half and led Liverpool to victory. Wouldn't have happened without him.
I think the fact that Gerrard plays for Liverpool who most people (myself included) on here hate while Messi plays in Barca is having a big effect. If Gerrard was a foreign player playing in Spain and Messi played for Liverpool I bet the votes would be the other way round.