There are some pretty big factors that haven't been mentioned yet, namely your connection and hardware. I have two computers side by side... and my daughter has her own account. She has a different video card and runs the game in a different resolution. Trust me... we don't see the same things. I can see a dots way off in the distance... PT's etc... long before she can. Lets just say... that kind of information is useful. =)
I used to live off in the boonies with a poor connection 125-250 ping times, and is it any wonder most planes warped out of the way right as I was ready for the kill?
OK... now that that is out of the way. With the same connection, same hardware, etc... I can still compare planes. Yes, I fly a dweeb plane (gave up trying to find one that wasn't) and it is hard to compare stats unless you fly one plane the whole tour... but one recent tour I flew P51D and had a 19-1 KD vs LA-7.... then turned around next tour and I flew La-7 and killed the P51D in similar ratio until I ended the experiment. I think the scale is tilted pretty heavily toward plane rather than pilot. You can't compare my KD ratios with yours and get that useful of data, but if we flew on the same system with the same connection, at the same resolution, same plane... etc... then we could tell something.
There are pilots who could fly a shoe box and kill me most of the time. They are very very good. At the same time... if I fly around and do nothing but cherry pick... I could get my KD ratio above 10. Would I be a good pilot? For that matter... what the heck makes a good pilot? The one that makes it home alive? The one who can fly inverted through a hanger? The one who can hit at d900 with a snapshot? The one with the most kills? The one with best ACM?
The cool thing is... it is for each of us to decide. Fly what you want, how you want, chose to give significance to this or that stat... or no stats... try to win the war or whatever turns your crank.
Sorry for getting a bit off the topic... but I would have to say pilot over plane. Plane is surely a factor, but I think pilot and how he chooses to fly matched with a plane that supports it.