I love my American heavies. T29 and T110E5 are my all around faves. I like T32 as well, but the turret doesn't feel nearly as God Mode as T29 because you'll be in T10 matches, though it's stronger than T29s. M103 turret isn't nearly as strong, but it's fairly bouncy, and it has decent mobility which somewhat gets you ready for the E5.
As for TD, Hellcat is my all around favorite, possibly in the game. T25/2 is forgettable. T28 proto was fun, and with high camo/camo net was pretty stealthy for me, but it moves like a snail. Decent gun. T30 is fun, and I use it as more of a sniper after the recent accuracy change. T110E4 has been decent to me, I just have to learn to play it better. Get some decent bounces with angling, which the enemy regrets as I hit him for 800+ heh.
Not much experience with American mediums past T20 (which I sold), and I don't have an opinion on them because I don't play them much. Just bounce my M4 crew between it, Ram II, and Super P for training.