>>14567188
Depends
Ravenstern has the best archers and mounted archers. I'd go for mounted archers so get some early cavalry which is rare in the game.
Empire for the best generic unit in all aspects. Crossbows are good and all infantry have their uses. Probably best to use their Gladiators and their crossbows if the mounted rangers aren't enough.
Fierdsvain have the toughest infantry, they act as the best meatshields and don't do much actual damage. Use the Huscarls as meatshields and gladiators to do actual damage, their berserkers are a little too fragile for my taste and the gladiator is a nice middleground between meatshield and glass cannon.
There are much rarer but better troops, mettenhiem for infantry and Noldor for archers.
The best troops are Knights and you can make your own custom knighthood order which you can customise into the strongest troops in the game.