I'm thinking of adding a light calvary and/or heavy horse archer to the medieval unit roster. It would probably have 8 strength to the Knight's 10.
There are no other land units with more than 2 movement except for the gunship with 4 movement. So is 3 too much for this stage of the game? A potential alternative could be ignore terrain movement cost.
Bonus question: Instead of speed this alternative cavalry unit could be a medieval evolution of the role the chariot played in classical warfare. The exact analogy would be 100% attack on Macemen, but do Macemen really need a mounted counter?