Re: which whey protein to use
Just a couple quick things here. The USDA recommends 50g of protein per day. For most people to maintain muscle density, this number is at the far bottom of the scale. Most conventional wisdom now says that 1g of protein is needed per lb of body weight to maintain muscle density. Many bodybuilders go as high as 2g per day per lb of body weight but this is on the high extreme and I would definitely not go any higher than this amount. I agree that the best source of protein is from your foods and protein powders should only be used to supplement your daily protein intake if you are not getting enough. A good rule of thumb for red meat, chicken, and fish is that 25% by weight will be protein. So, if you eat a lb per day, you would get about 111 g of protein.
As for what product is best. I agree that whey protein is ideal over other types of protein and avoid soy protein completely. Vegetarian proteins are not complete proteins, meaning they are lacking in one or more essential amino acids, so they should not be used as a primary source of protein. Soy protein also has some adverse effects with men due to estrogen.
To pick a good whey protein, you have to be careful as many companies do not come close to meeting label claims but provided the label claims are correct, you should choose a protein that is all natural (free of sucralose, ace K, etc) and look at the total amount of protein you get per container. In other words, one product may have 21g per serving and the other 28g per serving. Multiply this value times the number of servings to get the total protein per container to help you make the right choice. Some companies will claim 28g of protein per serving and then list a 50g serving size, meaning about half of your product is not protein (this is very common, so pay close attention).
I agree that whey isolate is superior but many games are played here as well, so pay close attention to the labels. Just because the front of the label says isolate does not mean you have a great product. Also, if you are not lactose intolerant, then going with an isolate may not be needed.