Just make sure that you get the commercial/industrial brutes that are stamped with NSF, those are safe. I'd get a 32 gallon Brute, but here is what I've found:
The 20 gallon brute can ferment 3 - 36 lb lugs, 4 if you push it a little, with 4 lugs, 108 -144 lbs, I believe that the cap is right up against the lid, but it's been a while since I made a small batch.
The 32 Gallon brute can handle 7 - 36 lb lugs or 252 lbs of grapes and still have enough room for the cap.
The 44 gallon Brute can handle up to 10 lugs, or 360 lbs but the cap will be up against the lid, 7 lugs fits perfectly and gives the grapes enough room to ferment, 7 lugs in the 44 gal. maintained the heat better as well.