If Brits can survive early-game somehow (maybe mgs?) double sniper + cromwell can carry for a while. For late-game it's about Fireflys and commandos/snipers.
OKW; I'd add the Kübel...it became an annoying little bug since rework and when it runs around the map grabbing all the point while impossible to hunt down without vehicles really kills the alied early-game. After that the Luchs comes out and finishes the job backed up by shreck bleb.
USF requires a good commander for late-game (Calliope), but they can do fine. Too bad they can't do shit vs snipers

Ostheer is in kinda dumb situation, T4 is hard to get, while T1-T2-T3 hardly works so ppl tend to go for Osttruppensb (they do 10000x better than grens) or T2 + Tiger. Tbh if it weren't for the PAks, MGs and Snipers, Ostheer would be dead.
Soviets: T1 is dead...only good for kübel hunting. T2 is viable even in late-game with Is-2, ISU-152, T34-85. Otherwise their stock armor is useless except T3 so they are still commander orinted. Cons do well behind sandbags, but don't expect much from them in late-game.
Now for the maps, some got rework but still has huge balance issues which I think causes most of the problems when 1v1 games are mentioned.