I remember back in the day, before they fixed the economy and raised troop prices, I had an army of over 7,000 Angmar orcs.
They didn't see much use aside from some crazy troop battles against other players, because of the lag, hahaha. On the server I play now, I have the funds to afford an army of similar size, but I've learned my lesson.
As a Dunlending player, I mostly stick to regular warriors, with about 30% of them being axe-throwers, and only ever a small force of bowmen. Reason being, in history, societies with similar levels of technology to the Dunlendings didn't employ many bowmen. (I suppose they didn't use any axe throwers either, but since we don't have javelin men, I'll cope). I usually have a banner-bearer for every 10 soldiers, I'm not sure if this is excessive or not, but it seems to work for me.
Berserkers serve as my officers and NCOs, since they have capes. I equip these with full sets of Dunlending armor, and give them legendary level weapons, to add a bit of extra umph. I hire one for every 10 troops as well.
I usually don't bring more than 300 soldiers anywhere at any given time, out of courtesy for other players, and myself.