For me personally:
F6F-5N 4.3 — > 3.3 or 3.7 (heavier but more firepower with x2 20mil and x4 50cals)
VB.10C-2 = 4.7 — > 4.0 (same as VB.10C-1 but heavier with x4 50cals)
yak-3 4.3 — > 4.7 (complete monster with the “poor ammo quantity” barely a downside and being strong in late-game AND in early game by climbing while also having lower repair cost than most 4.3 fighters)
Wyvern 4.7 — > 5.7 (c’mon is just obvious, no planes manages to upset even its own teammates, insane speed combined + 4 hispano MK.V cannons leads to a untouchable plane, not in the right hands only but also on anyone that doesn’t go “I gotta hold “S” to win”.
Sakeen 3.3 — > 2.7 (gaijin tries very “hard” to keep this plane at rank III, it just can’t. Maybe if they add more israeli wacky sherman modifications they can justify lowering it, but it will never line up a shot without sneaking around, and that powerplant is not making it easier, and mg151/20 is the worst 20mil, bad ballistics + questionable damage somehow)
g.55 serie 1 5.0 — > 4.7 (+0.7 BR for just replacing 2 12.7mm for mg151/20s is kind of overkill)
Me 410 B-6/R3 “strike” — > “Interceptor” (give it the same airspawn as the previous 410s and since it doesn’t have the climbrate of a BF-110, (which if you want to hunt bombers you have no problem doing so since it has a decent climbrate). If the 30mil hvap belt was the reason for the strike classification just make that belt more SP expensive)
Do-335 A-1 and A-0 + 0.3 BR (im not lying but I used them and they are so easy to abuse, I feel bad, insane firepower, climb and speed)
Ki-44-I 2.7 — > 3.3 (just absurd man, japanese 12.7mil are no joke and you put that already strong airframe at -0.7 BRs lower because instead of 4 it has 2?)
All of the zero line could get the compression issues it had in real life and could come down (IDK if A7Ms also had this issue)
Also belts are also a balancing tool, the BF-109 E-3 not only has no minengeschoß rounds but it’s belt is filled with junk (FI-T and FI), the APHE is actually the best round but it has the worst velocity, only having 120 rounds for 2 cannons doesn’t help.
In my experience, 5.0 long range bombers like B-17E/L, Me 264, M.B.162 are pretty decent if you hold a 10 degree climb and 90% of the time they ignore you since you will be like +5.5km alt instead of 4.8 km or lower (easy snack before main furball). maybe M.B.162 could get a little more SL multiplier, it’s repair it’s way too close to the SL you can make from a bombing run (payload for 1 base btw, but insane speed and climb compared to bombers). Bombers just need a way to not be forced to drop +5km in alt to rearm, they take forever to do so and leaves them EVEN more vulnerable if they try another run).
P.108 also doesn’t struggle, maybe noob hyperfixating on the “easy kill” but that’s it.
Pe-8 is just awful, slow, VERY SLOW, no decent climb, but it got a lot of bombs, simpleplanes levels of payload. feels risky putting at 4.0 but maybe BF-109 F-4, P-38s and XP-50s can still prove a menace to it
G5N1 and british bombers from 4.0 and 5.0 can’t provide since I don’t have them, I wonder why they have lower spawns (3.5km alt) specially the landcaster, ain’t that dude ̶s̶h̶o̶o̶t̶ ̶d̶o̶w̶n̶ ̶a̶ ̶F̶-̶1̶4̶ supposed to be next to the B-17?
Spoiler

if gaijin remembers to actually use repair costs and rewards as balancing tools (cough, cough 9K repair on bf-109 K-4) it would be appreciated.
that’s all, I heard early jets are horrible to play but im still preparing my SL banks to buy my first jet (Me-262 A-1a since it was the first I could buy so it’s going to be the first I play)
PS: I have played the Me-262 A-1 and realized, is DOGS###, DOOKIE EVEN, the attrocious RP required for mods and measly increase in RP bonus doesn’t help