N.O. products have never been scientifically proven to be effective at actually helping you build muscle, but they can at times give you a psychological advantage...But, I have tried a few

1. Superpump 250-Great pumps and energy, decent taste, but can give a bout of diahrreah shortly after using, and can be a bit annoying.
2. N.O. Shotgun-Great pumps and energy as well, equal to Superpump, as they actually share similar ingredients, but the taste of Shotgun is absolutely rancid.
As far as ingredients go, and the effects that they have I would try these two, as they seem to have been sucessful for numerous other trainers as well.