My favorite one so far is Bittrex because they are wokring great so far for me and didnt had any problems with them.Next one is Binance because they are paying me gas $ for my neo that i hold there
Thats one of the best features of BINANCE they give you your GAS and usually all the forks , also you can convert your leftover from trades in BNB
I am also most confident of Binance because it has very good support for investors. The low transaction cost is also a factor attracting Binance's investors, besides Binance's commercial interface is easy to use and integrates many technical analysis tools that make me very satisfied.