Here's the list of betting exchanges from Peeps' sportsbook thread. I haven't tried them all but I think Fairlay is the best out of them all and probably the closest to Betfair since they offer a wide range of sports. The only thing that sucks is their withdrawal fee ($25~) but it can still go down ($12~) if you earn enough vip points.
Thanks for your answer. This is what I was looking for. Fairlay, looks like the one with the most volume but I'm not too fan of the interface. Exbet, on the other hand, looks about right. Pretty similar to Betfair and it even allows us to connect Sports betting software such as Geektoys through API. The only downside of Exbet is that you can only use BTC. As for Sportx, it allows betting directly from your wallet using Ethereum. Would be great they could implement other protocols such as BSC or Polygon. As for Degens, it doesn't look much appealing and doesn't have enough volume.