I believe Russia will milk us dry to sell us their AL-51F1. Also it doesn't matter even if it beats F-135. The Engine not gonna make up for its sub par stealth of Airframe.
The Su-57, Su-70 and Su-75 are all treated with stealth even if we play along that the F-35 is more stealthy than the Su-57 it has overlooked simplistic weakness called, "flight ceiling"
If we have a radar and point it at the F-35
1st place for stealth
2nd place for stealth
3rd place for stealth (left or right side doesnt matter)
4th place for stealth
Last place for stealth
google ball parks the F-35 at 50,000 feet, ballparked the F-22 and 1st stage Su-57 at 65,000 feet and mig-31 at 81,000 feet. The Su-57 will see the front face but also the topside of the F-35 while the F-35 will see the front face of the Su-57 but also the bottom of it as well. I guess the best choice to make now for them is to continue with NGAD.