Now I am not trying to offend you, but have you fought good opponents with USF, or are you fighting people below your skill level? If I fight someone with an equal or better skill level, I can dominate the early game with USF but as soon as the mid game hits and the P4s and later the Panthers come out, you pretty much lose unless the map disfavors Axis.
Panther, Tiger, P4 < Jackson. Jackson out distances them all. If micro'd correctly you have the advantage. If they try to rush your Jackson have At to use Jackson as bait. Boom gg Axis. Rifleman outscale, have nades, smoke, scott wipes just about any infantry from a distance. Only thing that the Usf doesn't have is something to counter Elephant and Yag. By late late game, it's over for USF in those terms.