All depends on your point of view, the M4A4 is more important than the others - at least for my interests (and we all remember Pinky's opinion on the currently available options).
The M4A4, or the Sherman with the lengthened hull. Another important version, I agree! However, a plastic M4A4 (Sherman V) kit is available to us. It is made by PSC for Warlord Games, and while it might not be of Rubicon Models excellence, it is still a pretty good plastic model kit, and so much better than any resin kit.
That being said, the reality is that no one makes a plastic
M4A1 kit... yet.
...and/or:
A Sherman Jumbo... now here is an idea. How easy would it be to scratch build one of these using Rubicon Models M4A3 / M4A3E8 Sherman (Product Code: 280042)? Using plastic sheets (Evergreen Scale Models) it should be pretty easy to add the extra armor on the hull. The new casting for the heavier final drive assembly cover looked almost similar to the standard rounded cover, so just using part E26 might work without modification. I think the biggest problem would be the turret. Even though it was based on the T23 76 mm turret, there are some differences, but how easy would it be to convert the kit's turret into a Jumbo turret?
Oh, and you will have to use parts D20 and D21 because I think all the Jumbos used the track extenders. This was because of the extra weight of the tank.
Trivial Note: I would like to point out that the name "Jumbo" does not appear in any official wartime documents. It was simply called the M4A3E2 Assault tank. The name "Jumbo" came later after the war. Some say that the post-war nickname was created by a model company.
Even easier to make might be the Field Expedient Jumbo. We would start with the Rubicon Models M4A3 / M4A3E8 Sherman (Product Code: 280042) to make a Field Expedient Jumbo. These were created using 76mm gun armed M4A3 with HVSS by increasing the armor protection with additional armor welded to the glacis and turret. The additional armor was scavenged from wrecked tanks (German and American), but not from knocked-out tanks that burned - the heat of the intense fire compromised the steel. Other M4s were preferable because the entire glacis plates from wrecked Sherman tanks could be cut out and welded to the vehicle without needing to move gun travel lock or cutting a hole for the bow MG.
I have already assembled and painted my two M4A3 / M4A3E8 Sherman (Product Code: 280042). Now I have to order another one!