An idea that keeps popping every now and then, is to give different scores for killing different planes.

I made a simple XLS and that's the result:

Plane = Score
Sopwith Snipe = 34
S.S. D.III/D.IV = 32
Fokker D. VII = 30
Bristol F.2B = 28
S.E.5a = 27
Pfalz D. IIIa = 25
Sopwith Tripe = 25
Halberstadt CL = 25
Spad XIII = 25
Albatros D.Va = 25
Pfalz D. XII = 24
Nieuport 28 = 23
Albatros D.III = 23
Fokker Dr. I = 23
Spad VII = 23
Sopwith Camel = 22
Nieuport 17 = 18
S.S. D.I = 18

Just a couple words about it.
I computed EWFT, fuel, guns, stability, number of 120° moves, number of 180° moves and speed (2 or 3 hexes), divided every factor by the average of all models and gave the result a 10% weight.

Again divided total by average totals and multiplied by 25.

It seems quite fair to me, waddaya think about it?