Optimum Nutrition is the best pure whey supplement (aka ON).
Muscle Milk has more fat and while it mixes better with milk, it doesn't mix as well with water as ON does.
ON came out with a flavor called Extreme Milk Chocolate that, when mixed in water, tastes like Yoo-Hoo. serious.
If you want a good protein with no carbs and no sugar (also lactose free) i definitely reccomend Isopure. it is a whey isolate which means you absorb it pretty rapidly. it has a large protein content per serving too. tastes pretty good mixed in water. comes in fruit flavors. 50% of most of your vitamins and wont interfere with your diet since theres no carbs and no sugar. of course, you're gonna need a slow absorbing protein if you use this.
the Muscletech Nitro-Tech has a ton of BS in it. it has creatine too, which isn't always necessary and I personally avoid it.
Optimum nutrition is typically the best buy since the store i work at (GNC) sells it about $3-4 cheaper than the muscle milk and $9-10 cheaper than all the other proteins.
oh yeah- this place has great deals on supplements. you can get pretty much everything you need here: Home at DPS Nutrition - The Nation's leader in Discount Nutrition