Im with LynnCC, Brigham Chocolate Chip is the best!
But after that I do like Ben & Jerrys cookie dough, or chunky monkey, Baskin Robbins mint choc chip, and of course, Breyers vanilla which I have to use in my famous Frozen Mudslides. So, depending what Im in the mood for it could be a few different things, but in general, Brighams is my all time favorite.