For the sake of diversity here are a few opportunities the devs can look at-
1. Unique campaign lord models for each major culture like what was done in WFAS, I really don't like seeing my Irish lords looking like vikings.
2. More unit diversity, some factions need a kick in this area because all my armies feel pretty identical. Here is my bare minimum list:
Welsh bowmen - Welsh need a unit that really stands out, doesn't make sense to give the best archer unit to the faction that has the best infantry.
Beserkers - Make these guys recruitable at a pagan shrine in Noraway or Denmark.
Teulu - Some helmets with horse tails in the mix please.
3. Hornmen, Standard Bearers, and priest - Make these unit more available to the player for recruitment, I hardly ever can get these unit types.
4. Better Banners - There are some really missed opportunities here, for example no red welsh dragon or black raven banner WTF!!!!!!.
NOT to mention most of the banners need to be cleaned up a bit. For example the color field for most shields does not cover the entire shield and there is a white edge on the top or bottom of the shield.
Black raven banner
Red Dragon