Like someone already said, Whey Protein Isolate is probably your best bet, and Optimum Nutrition (from what I understand), is known for high-quality products. Although I don't use their protein at this time, I have in the past, and I feel like it was a high-quality protein that helped me reach my goals.
Although it is probably beneficial to have some liquid protein immediately post-workout, your overall, daily protein intake is more important.
Most experts recommend at least 1.0 grams per pound of body weight (going by lean mass may give you a more accurate daily amount needed, but measuring body fat % is actually quite difficult if you want to be accurate), so going by pound of body weight is fine and is recommended by most bodybuilders.
However, you must also be in a caloric surplus. Although protein is important when trying to build muscle, carbohydrates are actually even more important because they are going to be your fuel source for your workouts. If you don't push yourself in your workouts and don't progressively overload your muscles, you won't grow.
Also, since you had adequate carbohydrate intake, you don't have to worry about gluconeogensis (the conversion of protein into glucose for energy). This is a problem when you cut back carbs during a cutting phase, but since you will be in a calorie surplus, you actually don't need quite as much protein (in general) when trying to bulk--I'm not saying that protein isn't important when trying to build muscle...it is...it's just that protein requirements go down a bit when you are in a calorie surplus.
Thus, shoot for a calorie surplus of about 200-250 calories per day, and get at least 1.0 grams of protein per pound of body weight--and try to make sure that most of your surplus comes from carbohydrates since you need those for energy.
That was a very long response (lol), but I just wanted to point out that it's a little more complicated than most people think, lol