I am registered at others but I just started trading in June of last year on Coinexchange. I got my bitcoin from my credit card at coinbase and transfered it. All that was pretty easy to do. I am registered at about 8 exchanges but have only actively participated in 5. Nova (closing soon), coin exchange, crypopia, meractox (currently down) and coin gatherer (closed down and took everyones money luckly I only had under $20 in there). Coinexchange I have made the most in.