Binance isn't really
If Binance blocks access to US customers, where else can they trade ? As a European, I'm not familiar with American crypto exchanges. What are the most popular ?
Anyway, they can always use OKEx.
Bittrex, Bitfinex, Kraken, Coinbase if they count... but it's hard to say what "most popular" means since volume isn't necessarily popularity and neither is number of registered users.