As it stand in the current crypto market, Binance is standing as the king of all exchanges just like Bitcoin among all altcoins in my opinion. However, there are factors to consider when picking the best exchange, factors like fees, region, security among others. Besides these factors, Binance has gain a lot of popularity and has built some confidence among its users and participants.
I think that Coinbase, Bitrex, kucoin, Kraken etc are all going for the number 1 position and we can just watch how this competition will be.