As far as army quality goes, in my current playthrough I'd say that Brennus fields the best army in the game. Avendor started with a KotEG chapter in it and now he fields KotEG and Hammers next to his scores of Lions. Plus the always consistent Sarleon troops. He's a legend. His bad-tempered personality doesn't bother me either. I spend, as always, too much time in Sarleon so I cultivate strong relations with him. I'll definitely proselytize him at some point. Besides, bad-tempered lords are funny, contrarily to the sadistic ones who are purely evil. I tend to cultivate relations with Ealdred too, since his army is always fearsome with all those Black Archers in it. No reason not to do it, since I spend the largest portion of my mercenary time in Sarleon anyway.
As far as the pair of elderly pitilless/cunning lords goes, the Sarleon is king in that one too. Baron Aeldfried marshals an excellent army of many top-tier troops with scores of Lions included. As far as looks go (yeah, though not really important, I value aesthetics as well), he's ok, though I preferred his older looks. Now he looks as Valdis's twin with hair. Oh, he also rides an awesome Sarleon Warhorse. Cadeyrn marshals scores of Sarleon Rogues who I consider to be probably the best Rogues in the game after the Blackhearted ones. On the plus side, he tends to be an effective marshal and, fighting alongside and against him, I have to say he fights well. I liked his old looks, but, man, his new looks are AWESOME. Besides, as far as morality goes, yes, cunning personalities are more difficult to handle. But, if we give ourselves some pause and start pondering the lords' lines and general behaviour, we'll come to the inevitable conclusion that the cunning ones are definitely the most intelligent of the lords and I tend to value intelligence. The upstanding/good-natured/martial ones tend to be the most loyal, but a kingdom always needs its thinkers and politicians. And cunning lords excel at that. Now, if only the line to go kill a merchant wasn't there... This one somehow spoils their image to me. Still, I value the cunning lords and always keep some in my kingdom. And chief amongst them is always Cadeyrn.