I feel like Mechanized Assault is a bit of a newbie trap. Assault Grenadiers are just barely worth using since their dps is poor and their scaling isn't good.
Lightning War is easily the best Wehr commander since the anti-tank Stuka loiter is amazing. Also, Spearhead is awesome even if you never call in a mortar halftrack since Panzer Tactician is the most overpowered ability in the game.
Since you're an aggressive player USF and OKW are definitely the choice.
Remove both moscows from 2v2, add one veto and we are probably good.
For 1s remove kholodny winter, semois summer, Minsk pocket and we are probably good to go. Just veto Kharkov, semois winter (way too big for 1s). Oh remove la gleize from 1s too.