The best bitcoin and altcoin exchange in my opinion in HitBTC, they are the most flexible provider and have tons of different coins for you to trade. Additionally they have a very modern ui that is very easy to use and navigate, as well as a great mobile platform.
yeah.. I just signed up hitbtc as well..
However, the largest are still probably poloniex and bittrex :)
True, the main reason that I like them is mostly because of the very modern ui, its a much better user experience than the others.
Is hitbtc centralized or decentralized? I think we all need to get away from the centralized exchanges so we stop getting ripped off. What do you think?