Lets take su27sk and f16 block 20.
sukhoi has more powerful radar, would probably have better situational awareness, in multi aircraft engegements on both sides it could use that to position its forces better, unless we're talking about situation where awacs support is included, where sukhoi's radar advantage would be more than negated. RWRs would surely go off on both planes, giving some kind of info on broad area where enemy is, so f16 wouldn't be completely blind even at long range from sukhoi.
But lets stick to one on one engagement. Though not a a great radar, apg66v3 on f16 should be good enough to, given sukhois rather large RCS, allow it to use amraams to more or less full extent. Perhaps not to 80-100 km but realistically no one uses missiles to their max range. Note i am assuming c5 version of amraam or better. With diff weapons situation would be different.
sukhoi would use r-27 missiles as its main weapon at long ranges. While it would have to keep a radar lock to use the SARH version, it would probably fire off the IR version at the same time, just to increase its chances. Range on the basic version would be a little bit inferior to f16 but not by much (60-80 km) meaning its quite likely sukhoi would get to fire off its missiles before amraams get to it. Now, with SARH version that's not quite enough as if the sukhoi dies then the missile is useless too, but the IR version would remain on target, given its guidance isnt spoofed.
Differnt loadouts are possible, of course. Sukhoi could be using enhanced range versions of r-27, possibly up to 120 km, giving it a slight edge, though probably not able to kill the f16 before it fires off its amraams. Or f16 could be using aim7m, a SARH missile quite comparable to r-27, with some 50-60 km range. Please do note that in real world scenarios, all these missiles would be fired at anywhere from 25-75% of their max range, depending on altitudes and course of both planes. Or, if the pilot is an idiot, they'd fire them at 90-100% range and most probably miss as the missile would lose all its energy even to do a simple turn by the time it closes to the target. There's also IFF problem that we didn't even take into account here, usually making the engagement distances even smaller.
If for whatever reason both planes are alive to get to WVR, its aim9m versus r-73 would be relatively comparable though most people seem to give the r-73 an edge. While basic r-73 wouldnt be significantly better than aim9m, r-73m and subsequent versions do offer better seeker and added range. Still, a mutual kill would still quite possible as aim9m is a fine enough missile. With fight getting even closer, sukhois chances woulld improve, in my opinion as, though f16 has somewhat tighter cornering, combo of sukhois helmet sight and r73 slaved to it, especially r73m with even bigger offbore lock on envelope could prove decisive.
Of course, differnt versions of f16 and su27 would could offer different results. I chose mentioned versions for a reason though
