i have used both. simply protien is a good cheap post workout whey. i also liked simply gain, for post workout it has approximatyley 30g pro, 30 g carbs, and 5 g creatine per serving i believe. it was super cheap so i bought it, but i took double the servings to be more effective post exercise. many people have problems with some of the artificial ingredients in simply gain, like i said i didnt mind. but i prefer making my own post workout shake, with 50 g pro (usually optimum), 50 g dextrose or gatorade powder,and my own prolabs creapure. its alot cheaper this way. peace.