I own both but prefer the Dixon one. Its a larger and has the option of standing or galloping horses and drivers either at rest or whipping the horses, not to mention various passengers either shooting or just sitting being passengers!
Unfortunately the horses are still hippo like as you have said, but I think they are ok when painted up . If you were mixing Dixon mounted Cavalrymen with Foundry or Artizan ones then the horses would be noticeably different, but on a single based piece like a stagecoah or wagon then they work fine.
The choice of wagons from Dixon is pretty impressive, and I think his chuck wagon, buckboard etc are excellent.