Bitfinex has what matter the most liquidity. There are lots of different coins to trade with and you are able to sell any of them fast. Efficacy would be a great word to describe hows like trading here. Now under the blankets they also have a great support team, though you shouldn't be contacting them much aside from the verification, it is always good to have a good and fast one in times of need, time is important and in the long run having your problems solved fast means more profit. The UI iSee full review