Lately a new "Exchange 2.0" taking over. Bittrex & Polo suffer from many complains, locking accounts and many other issues.
Kucoin & Binance are quite different. they have their own token which give benefits.
Both are going very big in Asia and International.
Check out how Kucoin perform vs other exchanges:
https://www.kucoin.network/Your opinion?
Looks like they are taking over the volume though I haven't been trade on those exchange because I never had a problem with bittrex after they verify my account. I think their advantage are lower fee and bigger maximum withdrawal per day. I also don't use poloniex since they had a problem with support, I withdraw all my asset and transfer to bittrex.