i want to gain muscle and maintain low body fat.
Ahhh, don't we all. My advice is to give up now, because you won't. If you want to bulk, get a high calorie bar like the Kong or Tri-O-Plex bars. If you want to cut, I would probably stay away from bars period, none of them are that good.
Lean mass is attained by bulking and getting as big as possible, then dieting down, and then voila, you will be lean and with more muscle than before. Really, I have never seen someone add any appreciable amount of muscle without gaining fat, and if you can do this please post before and after pics as I would be amazed. I love hearing people say "My goal for this cycle is to put on 10 pounds of muscle and no extra bodyfat" ....it just doesn't work like that.