The Sherman appears in the game 3 times:
M4A3 75mm US Army
M4A3E8 US Army
M4A2 76mm USSR
The T-34 chassis appears 3 times, are you sick of it too?
T-34/76
T-34/85
SU-85
What about the KV series? The KV-1, KV-2, and KV-8, also appearing 3 times, yet KV-85's are a frequently requested unit.
Or maybe you're sick of the Panzer IV, which appears 8 times:
Panzer IV Ausf. G
Panzer IV Ausf. F1
Sturmpanzer IV
Flakpanzer IV
Panzer IV Ausf. H
Panzer IV/70 (Jagdpanzer IV)
What you wrote is just stupid...
How can you think of these tanks as similar ones?
T34/76,86 - SU85? Complety different role.
Pz IV G/F/H - Sturmpanzer, Flakpanzer, Jadgpanzer? The same as above.
KV-1, KV-2, KV-8 - same as above.
What OST can do for middle/late game?
Pz IV/Stug spam, Panthers, Tigers, Elephants.
What OKW can do?
Pumas, Jadgpanzers, Panthers, King Tiger, Jadgtiger.
What Soviets can do?
T34/76 spam, SU85, KV-2, IS-2, ISU-152 or Sherman.
What's the common thing? Nothing. Every single way is different than the rest.
What about US?
Shermans Spam, Jacksons spam, E8 spam, Bulldozer.
And what's is the difference between Shermans? Nothing. Better armor or a gun (which still is not late-game gun).
Making another Sherman
instead of something really new like Hellcat or Pershing is just boring and it gives you another late-game useless unit.
All you can do is go for Shermans and Jacksons or straight for Jacksons.
Jumbo will be no different than E8. Just better armor and maybe worse gun, depends what version.
I don't see any reason to choose Jumbo rather than E8 or stock Sherman since this one can be deployed around 4 CP while Jumbo will be 8-10CP.
By the way, German army was army of PzIII, PzIV and Stugs but I see more often Panther and Tigers than Stugs and even than PzIV (oh wait, there is no PzIII in CoH2. Weird...)