ItsAlwaysSomething,
I use Whey Protein - from Dr. Mercola, it's called Pro-Optimal Whey Protein. I love my proteins shakes - chocolate flavoured - and I add lots of supplements to it in combination with almond milk. The reason I like this particular whey protein is that it comes from grass-fed cows, no hormones, no antibiotics, and already has some digestive enzymes in it, which IMO makes it highly digestible and easy on the stomach. Even though I am lactose intolerant, I haven't had any problems with this. I make 2 of these shakes a day, to ensure my brain knows it's getting enough protein (in addition to other meals and plenty of snacks).
Alot of whey protein products contain lots of junk in them: HFCS, sugar, or other additives - so you have to read the labels carefully.
Many cannot tolerate dairy or casein, so they take hemp or pea protein.
It's something you'll have to try and see how you tolerate which products....
As far as quantity, I think it depends on the product. Mine comes with a scoop, and thereby a scoop of whey protein is equivalent to 17 grams of protein. I like to make sure that by 12 noon, my body has taken in at least 34 grams of protein (via the shakes).
Hope this helps.