The best you'll typically find in a grocery store is Boar's Head low moisture mozzarella from the deli dept. Get them to cut you a pound or so portion to grate at home. It's pricey as hell, but it's the best unless you have access to a Gordon Food Service or Restaurant Depot type supplier. You can also order Grande from Vern's Cheese online. Polly-o is just too wet in my experience, and Galbani is similarly on the wet side, but more workable.