Hi If you have a time, then you can choose the best place yourself by a search on Google And before check select, any broker kindly check reviews and reputation on different websites
BitMEX if you don't mind not being able to place an order for 30 seconds when price moves slightly. Deribit if you don't mind low volumes/liquidity.
With leverage? Why, look no further than the CBOE! http://cfe.cboe.com/cfe-products/xbt-cboe-bitcoin-futures/contract-specifications P.S. See you on the soup line!