Prefer the frontline warlord sovereign myself, but here's hoping all the playstyles mentioned here (and more!) will be viable in the final balanced game. It'd be great for replay value if it wasn't a bad idea to leave your sovereign in your capital, and receive a worthwhile bonus for doing so (superior administration or whatever), while your champions and children do the adventuring for you.
Even better if you don't have to lock your sovereign into a specific playstyle by the choices you make at creation (as it is to some extent at the moment), but can instead evolve his role as the game progresses and your needs change - perhaps start out as an adventurer and melee'er, pick up some magic as you level, eventually resign him to governing your capital as your empire develops and you have sufficient children/champions to do the running around for you. Or even the reverse, hide in your capital until you have an army to lead into battle and some spells to support them with, who knows.
I want to do everything; multiple viable playstyles that can change as a game progresses = replay value!