Leverage

Commodity futures operate on margin, meaning that to take a position only a fraction of the total value needs to be available in cash in the trading account.

Commission Costs

It is a lot cheaper to buy/sell one futures contract than to buy/sell the underlying instrument. For example, one full size S&P500 contract is currently worth in excess off $250,000 and could be bought/sold for as little as $20. The expense of buying/selling $250,000 could be $2,500+.

Liquidity

The involvement of speculators means that futures contracts are reasonably liquid. However, how liquid depends on the actual contract being traded. Electronically traded contracts tend to be the most liquid whereas the pit traded commodities like corn, orange juice etc are not so readily available to the retail trader and are more expensive to trade in terms of commission and spread.

Ability to go short

Futures contracts can be sold as easily as they are bought enabling a speculator to profit from falling markets as well as rising ones. There is no 'uptick rule' for example like there is with stocks.

No 'Time Decay'

Options suffer from time decay because the closer they come to expiry the less time there is for the option to come into the money. Commodity futures do not suffer from this as they are not anticipating a particular strike price at expiry.