Sappers have 6
Sturpios 8
Volks 7
Tommies upgrades have 8
so core infantries + pioneers
should be roughly the same
That is a bit scewed as you also need to account for fighting power and capping power. And after that the overall faction end game build and it gets very wild and speculative from there onwards.
I think it's easier just to compare the engineers by themselves.
Just judging engineers, I'd say OKW has the hardest time to get their stuff repaired because it's not that easy to fit in two Sturmpios as they're not useful in the late game (maybe that got better now with the patch), bleed you a lot MP and they're too expensive to just keep them in the backline.
Sappers on the other hand are great units. Decent CQC until the mid game, later on you can fit them with PIATs or LMGs. Due to the reasonable reinforcement cost they can serve as a meat shield for more expensive Tommies when not on repair duty. The only downside is that they often need to go into battle since they are the only UKF unit that can snare. That's also why having two of them has become standard.
So what is there to say for SOV and OST? Well, at least the engineers are cheap.