If PLAAF is considered biased then I don’t know who to trust… If Airshow is the only basis then you can argue that J-10 doesn’t fly as well as JF-17 when we both know that is not the case.
Well this is the defence industry, so of course they are going to be biased towards their own product. I expect nothing less. Also comparing the J-20 to a non-thrust vectored Flanker isn't exactly a high bar.
Besides an actual dogfight between two planes, airshows are the only basis for determining how agile an aircraft is. Airshows are the perfect place to flex that muscle, not only for entertainment, but for marketing and prestige. Anything else would be speculation and he said-she said. If the JF-17 puts on a better show than the J-10 then I'll simply assume the JF-17 is better in the maneuvering department, it is smaller and lighter afterall, but then so what? The J-10 is larger, can go farther, can carry more armament, better armament, has better electronics, larger radar, goes faster etc. All these planes nowadays are BVR queens anyways, launch the missile and rtb.