I use a soy protein powder for two reasons...
1. I'm an Ag major and soy is one of the hottest commidies to show versitility in the market, so I try as many soy products as I can (candles, cheese, haircare stuff, etc)
2. I know the process by which whey protien is derivied from and it kinda makes my stomach queesy (nothing bad really, it's a by-product of making cheese)
I have only tried the vanilla flavor so far, I figured if I wanted to flavor it I could throw some fresh fruit in the blender with it. The texture is just a tad gritty, but really not that bad
And it's quick and it elliminates carbs, so it works for me and my lifestyle.