I'd like to share with you some of my ideas (some of them have probably already shared on this forum, sorry for that) to improve Panzer Corps.
1. Adding more versions of the Panzer 38(t) as they were improved (specially armor) during the first years of the war and was one of the most common tanks at the beginning of Barbarossa (they were more available than Panzer IV with 754 units compared to 517 Panzer IV kurtz in June 1941).
2. Change the name of the Panzer III J/1 to Panzer III lang or L/60. Icon should be changed too (same as Panzer III Ausf. L).
3. Panzer III Ausf. M (and some L) were equipped with side armors (Schürzen) like Panzer III Ausf. N, icon should be changed too.
4. Late Panzer IV Ausf. G (less than half of the total production) were up-armed with longer gun (7,5 cm KwK 40 L/48) like the Ausf. H. You should introduce them as Panzer IV Ausf. G (L/48).
5. Panzer IV Ausf. J has strictly the same gun as Ausf. H but a slower rotating turret.
6. Panther since the Ausf. A has AA capabilities.
7. Jagdtiger has also AA capabilities (mounted MG-42 on top of the superstructure).
8. StuG IV has the same armor and gun as the StuG III Ausf. G (which is officially a StuG 40 by the way
): 80 mm front for the bow and the superstructure, plus side armor. Values should be the same (the rear of the StuG IV is indeed a bit less protected). I don't know why you can switch direct-fire to artillery for the StuG IV and it has a two hex range... Wired. StuH 42 should have a two hex range instead.9. Sturmpanzer IV is missing (also known as Brummbär).
9. Weapon switch: on of the greatest ideas of PzC, but it would be good to add the switch weapon to more units, for instance those armed with 2cm Flakvierling, Wespen (which embark few antitank shells), 10,5cm le.FH 18, etc.
10. As I previously said in another thread, it could be interesting to add the antitank version of the T-34, the T-34/57 which fight near Moscow in late 1941 (and reappear in 1943) as a special unit and remove all KV-5.
11. Way too much SU-85, SU-100 and IS-2 in the original campaign scenarios or GC in 1943-1945 (Bagration and Lake Balaton have been since patched), and too few T-34 (76 or 85), T-70 or SU-76M.
12. T-90 SPAA project was canceled in 1943 and therefore could not be available in the game. You should replace it with quadruple AA machine gun mounted on American trucks or towed AA artillery.
13. Antitank self-propelled gun SU-57 (aka T-48 GMC) is missing (US M1 57mm gun mounted on M3 Halftrack). About 650 issued to the Soviets.
14. KV-1 has improper denomination. The game is using the German's code-names for this heavy tank (A, B, C, etc.). You should use:
KV-1A : KV-1 obr. 1939 armed with the 76.2 mm L-11 gun (same as T-34/76 obr. 1940)
KV-1B : KV-1E obr. 1940 with a better gun and additional armour-plates (bolted).
KV-1C : KV-1 obr. 1941 heavier version with improved gun, a bit less amour than KV-1E.
KV-1S which does not exist in PzC: a lightened version (and faster) of the KV-1.
15. T-34/76 obr. 1941 has a wrong image. It actually depicts a T-34/76 obr. 40 (see the gun).
Introducing quota control
My last comment is a conceptual criticism, a problem inherited from Panzer General: the game should have introduced a quota control. You can't add to your roster many Tiger, Panther or heavy Jagdpanzer. Rare units should be limited and both player and AI should have the obligation to respect historical quotas. For instance, you can't purchase 3/4 of Panther for 1/4 of Panzer IV lang, having no Panzer III in 1943 or too much Panzer IV lang in 1942.
In other words, roster should be more balanced. Or AI won't be allowed to purchase 6 Tiger I during a game, as I previously experienced during the "Zidatelle" offensive, playing the Soviets!
Quotas for the German side should be removed for the USA invasion, but are missing in the Grand Campaign.