first off you don't need a protein powder to build muscle.. that is probably the #1 biggest myth that guys believe.. you can thank BILLIONS$$$ in marketing that makes you believe that ..
having said that if you must choose a whey protein you probably won't find a good one at walmart or GNC.. read the ingredients, check the label.. if it has garbage in it then avoid.. it should also be an ISO.. very important. n2bm sells a good protein whey which has like 6 ingredients and isn't sweetened with garbage like HFCS