For centralized exchange for the better choose exchange that has full regulation, like Bittrex,Poloniex, Liqui, Binance, Bitfinex, Cryptopia, HitBTC. But I personality used Bittrex because here the volume is bigger than others and Bittrex also has full regulation based USA. And for decentralized exchange I used EtherDelta, in this exchange available all ERC20 token and this also good exchange because we got the private key, so we have full control of our money there.
Bittrex is becoming increasingly difficult to use and the number of Altcoins listed on it is increasing, but the stability is very low. Exchange interfaces with the newbie are hard to use, and the amount of dives is decreasing. Replacing Bittrex, many traders choose Binnace as having more potential as they develop their tokens and friendly interface, which is easy to use.