OKW and USF suffer from a lot of the same issues, lack of support weapons, little in the way of good builds outside of the standard cookie cutter, low amount of doctrines, ect.USF and OKW don't lack support weapons, they just aren't any good. Buffing the leig, pack, and .50cal would go a long way in diversifying these factions. OKW also has a lot of what I would call "support vehicles" rather then many support weapons.
But two things that makes me like playing OKW more is the more interesting tanks (Relic REALLY messed up with how few of the Sherman varients they put in), and you have a much much wider selection in the infantry you can get.
I would have a lot more fun playing USF if you didn't have 1 infantry unit and nothing else.
US might only have rifles, but with 4 different upgrade options they come in many diverse forms. Also okw and USF have more forms of "support infantry" like pathfinders, jeigers, and assault engis.