Quality-wise, on average you can say the Chinese Flankers are at least on par with the Russian flankers. Russia has 260 Su-27s and a limited number of other types, while China has somewhere in the range of 200-300 including the Su-30's with the navy, someone will have to correct me on the exact number.
The only other 3rd gen fighter Russia has is the Mig-29.... which no sane person would even try to compare to the J-10. I'm sure the newest versions of the Mig-29 is in the same ballpark as the J-10... but you gotta check out with the Russians actually have in their inventory. I heard a few years back the Russians grounded their ENTIRE Fulcrum fleet... not sure if they got any flying right now.
Only other fighters worth mentioning are the Foxhounds/bats they still have that are partially serviceable.
Correction: Some sources indicate that the Russians have as few as 195 Flankers left... can someone get a more accurate estimate? Wikipedia indicates that the Russians have 195 Flankers, 190 Fulcrums, 147 Foxbats, and 39 Foxhounds for a total of 571 fighters. Wikipedia indicates the PLAAF has 190 J-10, ~280 Flankers, and 180 J-8 for a total of 550 BVR capable fighters, with an additional 190 J-7s.