Investors' optimism over marijuana's future has turned Tilray Inc. (NASDAQ: TLRY) into the biggest marijuana stock by market cap; however, Aurora Cannabis (NASDAQOTH: ACBFF) and Canopy Growth (NYSE: CGC) are much bigger companies based on marijuana production and revenue. Could they benefit more than Tilray from Canada's approaching recreational market?With only 17.8 million shares available to trade, Tilray's shares are more exposed to breathtaking pops and drops than are those of Aurora Cannabis and Canopy Growth.