The worst, debauched and pitiless or whatever in other mods, should be last in the line, give them a village but never a walled fief.
Sometimes martial or cunning lords, but I personally just stick with the above, as the latter gets pissed off when you dont give them 3 fiefs soon enough (I think one must be a walled one, as they still get pissed off to me when they have 3 villages). Walled fiefs, towns and castles should be given to good natured and upstanding Lords.