Which protein powder is the best?

So today, the Rebecca, the Eco-cowgirl, writes about protein powders.

One of her friends had a brownie recipe calling for protein powder and the store had so many choice that it became confusing to know which was best. 

The Eco-cowgirl writes about protein powders here:

I totally understand the confusion on protein powders. There are so many options and even in natural food stores carry powders that aren't healthy. I'm with you that we should stay away from most soy-based products. We already have way too much estrogen and estrogen mimicking compounds in our environment.
So far from my research the best quality protein powders are hemp and whey. They have the complete amino acid profile our body needs and are the most bioavailable sources for your body

We already have too much estrogen and 
estrogen mimicking compounds 

in our environment.

I'm still on a mostly vegan diet so usually use hemp-based protein powders. The downside of hemp is that it can be a little harder do digest if you're not used to the fiber content and isn't usually the best tasting unless you blend it with something a little tastier like fruit. I like to use Manitoba Harvest brand hemp protein powders (chocolate is my favorite http://manitobaharvest.com/

And another good vegan brand that is better tasting and a little easier on the system when you're just starting out is Vega protein powders. They are a blend of sprouted brown rice, pea, hemp and saviseed protein, so you still get a complete protein blend and some of them even have greens added to them for an extra kick of nutrition. http://myvega.com/

I'm not quite as familiar with the whey protein powders since I haven't looked at them for a while, but I would suggest making sure they are from grass-fed cows that haven't been given hormones (rgbh). Some people say that concentrate is better than isolate because is it in a more whole food form, but I'm not sure that it really matters as long as the whey is from a quality source.
Another thing to look out for and try to stay away from is artificial sweeteners (splenda, aspartame, sucralose, etc.) and fillers (artificial flavors, soy lecithin, cellulose gum.)

stay away from is artificial sweeteners