[pdovy]

USO is probably the biggest, most liquid one available in the US.

Almost all of these funds will hold some combination of cash, short term debt and oil futures, with the ratios depending on their target leverage.

Performance between them will vary depending on, among other things: whether or not the ETF is levered, which particular type of crude it's tracking, it's time horizon, and how effective the fund managers are at rolling their futures holdings.

NOT investment advice. Commodities are fickle.