Could China's J-20 Stealth Fighter Beat Russia's Su-57?

https://nationalinterest.org/blog/buzz/stealth-battle-could-chinas-j-20-stealth-fighter-beat-russias-su-57-97917

1. the Su-57 is neither better nor worse than the J-20 but fulfills an altogether different operational purpose. The J-20 was designed as a stealth missile platform that can penetrate sophisticated air defenses in order to target critical infrastructure or military assets. The Su-57, on the other hand, excels as an air superiority platform that trades stealth and ground attack features for raw dog fighting potential. Thus, RG aptly characterizes the thrust of the Russian export argument: China’s air force should buy the Su-57 not as a replacement, but as a complement to the J-20.

2. the J-20 “is based” on the ill-fated MiG 1.44: "In my opinion, the machine is based on the Russian MiG 1.44. That plane was created to compete with the PAK FA at the preliminary design stage, and made its maiden flight in 2000. The Chinese plane is very similar. Although it hasn't been announced officially, the J-20 uses our AL-31F engine, developed by Salut, which the Chinese bought for half a billion dollars." The article went on to cite a similarly-shaped canard configuration and tail section as examples of an allegedly uncanny resemblance between the two fighters.

3. Apropos of engine troubles, Russian defense commentators join their western counterparts in their skepticism about the status of the WS-15 engine that the J-20 was supposed to ship with. Performance and reliability issues with the WS-15’s  single-crystal turbine blades has led the Chinese to produce initial J-20 batches with older, inferior WS-10B’s as a stopgap measure. There was a brief spurt of speculation in 2018 that Chinese engineers had managed to fix the WS-15, but nothing has been confirmed as of the time of writing.