UCO is a high-risk, double-long oil market exposure. The Fund attempts to track an index on a daily basis. See why I conclude oil futures prices are overvalued.
DBO provides a crude oil futures exposure in an ETF. Its long-term return was negative and its maximum drawdown unacceptable. But it can be useful for short-term oil trading.
DBE tracks an Index of energy futures long positions. There is a high risk of an oil price collapse if Iranian oil is released on the market, and DBE would suffer greatly in that event.