Probably water, followed closely by food. Just be careful not to overdose, as it's known to cause fat deposits to form on the legs and midsection.
Of non-hormonal stuff I'd recommend Activate Xtreme or Animal M-Stak probably. However, non of the non-hormonal stuff is gonna do much unless you already have your training and diet spot on. Enough rest, proper nutrition and lifting heavy weights is the key to building muscle:good
