F-35 as a plane is mediocre compared to say Su-57. I'm willing to grant that if Su-57 is to challenge F-35, F-35 loses. The thing is F-35 carried through wont be challenged by Su-57 as F-35 is a basically a flying platform. Where Su-57 is optimized for single unit operation ( and Soviets and Russians absolutely excel in that ), F-35 is optimized to be able to operate in a diverse group. What it sees, C&C sees. Until Russia or China get there, F-35 will be massively superior to anything else. For F-35 all fighting is supposed to be BVR.