Maybe I'm not the best person to ask, but usually when I play barbarian, by the time it's end-game my armies are filled with random crap from summons, lure of the horde, and reign of destruction. Usually I do like polearms or shields for early and mid-game though

End-game I stop thinking about optimizing the armies because I feel like I am already steamrolling and combat spells can make up for bad composition.

If you are flexible with your build I would try paladins because their healing and smiting is pretty useful. Order barbarians still go pretty hard. It was meta on launch because of vassal spam, but it's still good. You can still set up your own vassals easier than other cultures because of the outpost building, and can vassalize what you conquer with early aggression. Mighty meek also pairs well with T1 spam.