Was thinking, the rohirric heros
So Hama, Gamling, Elfhelm
For Gondor, gondor captains would be good, Madril, Halbered maybe ~Belegond
Mordor, like 2 extra Nazgul, Gothmog, mouth of Sauron
Isengard, Ugluk, Sharku, maybe some uruk captains
And for campaign, just all the herosd added, with harder AI
Now i know, there arer mods that adds all these, but not a mod that adds everything/
Rerturn of Shadow is the closest i found, but the ai is still easy, and it bugs out a lot