I have been using obers more lately which are very effective with veterancy but are sometimes hard to keep alive
I think Obers could use a small performance buff, either by giving them a fifth model (same DPS tho) for survivability against mid-late game indirect fire or by moving them to mechanized truck so they can hit the field earlier and don't have as much of a vet disadvantage as they have now. Stuka could be moved to panzer HQ.
I feel like once OKW starts losing the mid game infantry engagements (against penals, guards, rangers, airborne or double weapon tommies/riflemen) they can't really recuperate because their own elite infantry hits the field too late and dies too easily to explosive/indirect weapons.
Vehicle wise OKW is strong enough IMO. Especially now that the Panthers are really good.