Hi,
i think the Me109 in almost all versions was the best fighter all over fighter.
Not only cause the highest scoring aces flow it (not only germans!) but it was pretty good at all altitudes, had a very good acceleration, very good slow/mediumspeed-manouverability, had the exact working nosemounted guns and many Rüstsätze to provide a wide field of usage.
Of course the Spitfire had some advanatges, but it had a to slow diveacceleration, while the P51 had a to slow vertical and climbacceleration and the FW190 had simply a to high wingload and so a bad turn and stallbehaviour.
The FW190 probably was the best attacker/destroyer with a good chance to evade attacks due to its rollratio, but in my opinion the 'best fighter all over' need to be able to dogfight better. Sure before the SpitIXc the FW´s was the better fighters vs the allieds, but testfights between the F4´s and A3´s did show that the 109 was the better dogfighter. The mainadvantage of the 190s was their incredible firepower and highspeedbehaviour.
The SpitfireIXc cant be the best all over fighter, cause the best all over fighter should be able to catch its oponents, but the 109´s and FW´s could outdive it by easy, the Spit14 would fit more i think.
I realy also could agree with the Yak3, but its range was pretty poor so it was 'only' a short range interceptor, similar to the Me163(of course not that short).
Iam pretty sure that the P51, if the 25lb(or higher) boost and 2000HP or more would have been available, would be the best WWII fighter, but without it was somewhat underpowered(i think it was like the 109D in Spain, very good but still underpowered to show its full potential).
So my choise is the 109, with a short exception in late 1943, when it did wait for MW50. It did well in France, it did well in BoB, it did well in Africa, it did well over germany and it did well over russia and that in many cases with a big disadvantage(BoB: bad range + bad close escort command, later: less in numbers)
BTW, if we choose the planes cause their results, i guess the B-239(Brewster F2A1) would be the best WWII plane. 496kills vs 19 loses is a impressive result. But if we compare the US-Brewster results(which had a better performece than the B-239) with the finnish results, we can see easy how important the Pilotskill and tactics be.
I think its a myth that the 109 was bad after the 109F(1941), born out of the unexpected good results of the FW190´s vs the SpitV´s and the complaining of a less good handling due to more weight by the turnfighters among the pilots and of course cause the high LW losses again a enemy with more planes and better getting pilotskill. But if we try to focus the fighterperformences only, all other fighters also got a higher wingload, what wasnt a big problem, cause in planes with 1500-2200PS and combatspeeds above the Vmax of the earlyer versions the time of classic tight dogfight was over. Hit and run was normal, not very tight slow fights. Later in the war Hartmann´s tactic was profed as the right tactic, the turnfighters got wounded or was dead, while Pilots with Hartmanns tactic rarely got in trouble(Hartmann´s mechanic never had to repair the plane cause enemybullets and he never lost a wingman), and Hartmann did enter service in late 1942, when the 'easy' time already got to its end. He made rundabout 1400 missions, 700 with contact, all in 109´s. His plane must have been a good one, next to his skill. I wonder how his tactic would have been with wingmounted guns?? On 50m distance he would have had more problems. How the 109G/K´s would have perform if all new german pilots would get teached by Hartmann with the same time in a flightschool like he had??
Of course thats only my opinon and what is the best fighter for sure depends in big degrees to the tactical/strategic-need.
P51 = best long range escortfighter
P47= best high alt escortfighter (easyer kills for newbes cause the firepower)
Typhoon/Temp = best groundattacker (easyer kills for newbes cause the firepower)
FW190, F4U = best attacker(easyer kills for newbes cause the firepower)
SpitIXc, Yak3, A6M=best turnfighter
Spit14 + 109´s+La5/7, F6F, N1k , Ta152H1 = best all over fighters maybe.
As most important fighters of the war i would chose this planes:
P51: not the best, but with its range and tactical advantage while the escort, it made the Bomberattacks deep over germany possible.
Hurricane1: It was there when it was needed and was a good gunplattform, in combination with the radar it was able to face the german fighter/bombers out of a tactical advantage.
Me109: Always a good choise again nearly every oponent and in every altitude.
P38: In the pacific it was the 'me262' among the slow japanese fighters in 1942/43 and got more kills than any other US plane vs Japan.
I think no type of the russian fighters was very important, for me it seems like the number of planes and pilots brought the result, Stalin simply didnt care about loses.
The FW190´s came to late in big numbers to be realy important i think, they had their good year in 1942 in the unimportant channelfront. In the east and Africa the 109´s brought good results and since 1943 the FW´s had problems to hold their hands up, cause the higher getting number of enemys and less good dogfightqualitys specialy in high alt and it was less easy flyable, so the decreasing pilotskill brought even more problems in this heavy planes.
So i think this great plane came in the wrong moment and to smal numbers to get realy important, same like the SpitIXc with its short range.
I think the Airwar got won in BoB by the Hurricane in combination with the radar and the short 109 range and later by the endless supply of the allieds and here specialy the russian Airforce and the tactical advantage of the P47´s/P51´s above the Bombers and it got lost by the totaly naive and stupid german HQ with a addicted leader and a 'Führer' who never got the right informations cause all did fear him, what caused a to late supply with many and the right planes and the downfall of the good german flightschools(they took the teachers into combat, how stupid they must have been?? Imagine a droptank for the E4 while BoB! ) and so the Luftwaffe itself.
Oh, that was long, time to work!

Greetings, Knegel