I think I'm going to have to go with the 18x20. Since I am having such trouble deciding, either one would work for me. I tend to hit a flatter ball though, and the 18x20 seems to be the best choice in that regard. I get plenty of spin with it as well. Great frame!
Head Graphene Speed Pro LTD, Weisscannon Scorpion 17g (50 lbs)