I like Kraken....but perhaps not so good if you are rolling around in trades with 50 BTC or whatever.....

Bitstamp is the most established and most 'shenaningan free' of the large exchanges, but they only offer very limited trading tools...Buy, Sell, Stop, Market and Limit. No leverage. No shorting.

That leaves Bitfinex, Huobi, and OKcoin.......a man takes his chances in the Wild West.