I just opened a 3x short position on $BTC on @protocol_fx. They recently launched their second season of a trading competition with a prize pool of $20,000. The top three winners will each receive several thousand dollars, and anyone in the top 100 will receive $100. One advantage of this platform is that there are almost no funding fees. Because its leverage is achieved through collateral and synthetic positions generated via protocol accounting, there are no counterparties, thus eliminating funding fees. This makes it relatively friendly for medium- to long-term trading.