The sensible way to apply a ENY and/or perk value to a tank is to take each of the attributes and put them on a slider. Armor, main gun (AP/HE ability and reload rate), and speed are the biggest three attributes. Then ammo load, MG's, turret twist rate, gun sight, turn radius/pivot ability, etc, can all be rated as well.
And just a reminder best to worst in AP ability in AH:
King Tiger/Jagdpanther
Firefly
Panther/Jagdpanzer IV L/70
Tiger
Panzer IV H
M4A3 (W) 76mm/M18
T34/85 (HVAP brings it up to par with M4/76 and Pzr IV H out to 1200 yards)
Panzer IV F2/Hetzer
M4A3 75mm/M3 Halftrack 75mm
T34/76 (HVAP brings it up to par with Pzr IV F2 out to 1200 yards)
M8
Panzer IV F1
The best HE platform in AH is the M4/75mm, hands down. HE damage of 178 lbs, a reload rate of 4 seconds, the ability to carry 60 rockets (Calliope), and 97 rounds of ammo allow of it to make a town white flagged all by itself. No reload needed. Oh, and no worries about losing perk points if you get caught.
FWIW, the King Tiger, Tiger, and T34/85 all do 234 lbs of HE damage; the M4/75mm does 178 lbs dmg; the Panther, all 3 Pzr IV's, LVT4, and T34/76 all do 156lbs of HE dmg; the Firefly does 140 lbs, the M4/76 and M18 do 103 lbs, and the M3 Greyhound does 31 lbs of HE damage. Town buildings, ord bunkers, radar towers, fuel tanks, and barracks all need 312 lbs of damage to be destroyed.
I have not confirmed the Jagdpanther, Jagdpanzer IV L/70, or the Hetzer but if they fall in line with their parent gun the values will be 234 lbs, 156 lbs, and 156 lbs, respectively.
Speeds are a entirely different category in itself. We all know the speed demons (M18, M18, M3/75mm), and we all know the knuckledraggers (Firefly, Jagdpanzer IV L/70), and most of us know to exploit certain weaknesses in certain tanks (VERY slow turret traverse rate in Tiger, no turrets in Jadgpanzers, lack of long range ability in T34's, etc), so be careful in asking for a ENY or perk cost based on 1 or even 2 features.