Good question. Vitamin Shoppe, bitches!
I use to go to GNC a while ago but stopped because of their prices and horrible service. Everytime I went in there nobody knew anything about the products or anything.. half of the employees were all fat. I just go to vitamin shoppe now.
To me, it's not a case of either/or. I shop at both GNC and Vitamin Shoppe. Vitamin Shoppe is GREAT, because of their name-brand products (i.e. those from the BodyTech line), which are just as good as the more commercial brands. In fact, for those lamenting about the rising price of whey protein, I'd suggest hitting Vitamin Shoppe hard, as their 5-jugs of Whey Tech run for $25.
Another great product is called Crea-Tech Extreme. It's basically BodyTech's version of CELL-TECH (except that it contains Corosolic Acid, instead of Lipoic acid, to aid in creatine and dextrose absorption). And, unlike that of CELL-TECH, the Orange-flavored version of Crea-Tech Extreme tastes terrific.
As for GNC, the cashiers can look like WWE's Umaga, for alll I care. As long as I can get the brands I like (with the marked-down prices) and use my Gold Card to get those RTDs, protein powders, and certain ON and MuscleTech products, I'm a happy guy.