Use sometimes bitfinex as well, but I don't appreciate their attitude towards customers. Bitrexchange is better in this component in particular. And on speed as well.
Bitfinex is an exchange to avoid IMHO. If you do some basic level research, it becomes clear that there are a lot of unhappy users with withdrawal problems of mainly dollars, and this has been the case for over a year.
Bittrex is better, but their compliance model makes them super paranoid to the level where they in some cases block your account to ask for new information to confirm your identity.
I get why they do that, but there are other compliant exchanges that bug their users far less often. I do however agree that Bittrex's exchange is pretty decent overall---an A+ score for their trading engine and overall responsiveness.