If one is trying to "fill the gaps", I'd start with the Panzer III, M18 (or even M10), StuG III, and Su-100. All four represent something we do not have in AH at the moment, AND were very prominent in WWII. The King Tiger, any of the Soviet JS/ISU, the Pershing, Comet, etc were there too late and contributes too little in comparison to the workhorses of the war. I vote to leave them out until the "gaps" are filled.
If HTC were to add the Panzer III (w/ 2 main gun options), StuG III (with 2 gun options to span EW-LW), another variant or 2 to the SdKfz 251, and re-model the Panzer IV H, they not need to add another German gv into the game for another 10 years (2 new German GV's, a re-model, and a addition).