Hero and commander leveling depends on the commander's specialization.

I really like the Block skill, the Unstoppable ability with 2 attacks, and the Deadly Gaze skill; in the upgrade options, it can be changed to Poison, which is also good (according to the options I've set). I would rank shooting as secondary, along with the high-speed bonus for cavalry, but the 50 HP regeneration on later stages of the game seems pointless to me, because the Expert War Arts skill is much better.