Just go with knight x 2 + mage x 2.
With some points in forge (and a lot of gear has + forge), both your knights will always have high dps weapons. And you can easily have both mages invest in 3 different schools of magic, thus providing heals, dps, buffs, etc.
Also if you go double mage, it's not a bad thing if they have some magic schools in common, so their spells benefit from the same debuffs on mobs (eg: it's better to throw lightning than a fireball at a mob that has just been made wet by the other mage). And don't forget about the sorcery school, it has some nice spells too.
Last thing, it's good to have one mage with high leadership.

Anyway from what I've read here and there pretty much anything work.