In 0.86 and previous, there are Empire champions and Kingdom champions.  Kingdom champions won't work for Empires and vice versa.  Why aren't there champions that will work for either side?

With the faction differentiation work being done one Beta 2+, where factions are good/neutral/evil and lawful/neutral/chaotic, why not have champions that will only work for lawful factions, or evil factions.  That way each faction will also have a unique feel because the champions you can hire will also be different than other factions.

In order to have the number of recruitable champions in a given game be reasonable, each champion should probably only have one preference or only a small fraction of the available champions would be hirable.  Or you could make some of them "will not work for X" rather than "will only work for X".  As long as about 50% of the champions are hireable for a given faction.

As an alternative, the current build also has a discount to the hiring cost if the champion is the same race as the faction.  You could work in a penalty if the alignment is off, though this might favor neutral factions.