KuCoin and Gate.io are the biggest available at the moment. More to follow, among other things, Binance. If you want to trade, I would currently recommend KuCoin.
Binance is very slow to allocate airdrop Symbol to NEM holders. They even don't allow to withdraw XYM out of Binance today. It sucks in my opinion. They act like a dictator in crypto.
I would be happy if the domination of Binance will be shared with 2 or 3 big exchanges.
Kucoin has grown very well as I recalled that they have some troubles in 2018 and 2019. Now they are on the top of crypto exchanges.
Do you know if Binance has given any timeline on when they will list XYM? The volume currently seems pretty low - hard for price discovery.