Me 262 - 150-200 perks
Tempest - 50-70
Spitfire Mk XIV - 20
F4U-4 - 15
F4U-1C - 10
Ta-152 - free or 5 max
is my opinion.
The Spitfire XIV would have a better K/D if people wouldn't take it down low and start turning hard with it. I've seen three XIVs in my time playing. One was flown well, kept fast and tore up everything in the area. I stayed low and out of it's way in my Spit I. The second one tangled with me in a Spit I, and if it wasn't for an La-7 and Rude's P-51D coming in, I think he woulda goofed up and let me get him. (let's say I was droolin' even with the La-7. It was Rude's P-51 that got me to where the Spit XIV could hispano me.) The 3rd one came in low over the hills in that island in the southwest of the Mindanao terrain. I was only at about 5000 ft, but I dove down, caught and killed him in about 7-10 seconds in a Spitfire V. Point is flown right, this is a 20 point perk ride easy.
I've never even seen a F4U-4... *shrugs*
Me262 and Tempest stats speak for themselves. I dunno, maybe if people flew the Spit XIV (and F4U-4) like they do the Tempest, the K/D's would be about the same.
Ta-152 K/D isn't that much better than the free D-9. I say unperk it for a tour or two and see what happens.