A succesful perp dex probably should have: Top UX, regulatory compliance and descentralization
Extended has:
-Best UX
-Compliance focus & TradFi partner will show why
-Built on top of Starknet without control of settlement layer
Overall Extended has best total score
First things that comes to my mind when I think Extended.
But TLDR: There is no second best and expecting more at scale imminently