Danes: Huscarls vs. Feudal knights, Norse Swordsmen vs. Dismounted FK

[Odin]

I never bother with DFK as danes because they are very slow and exhaust too quickly. Dismounted huscarls and viking raiders are effective against armor and a lot faster in movement.
Viking raiders especially are still good in late game due to 3 possible armor upgrades and 60 men a regiment

Never bothered with norse swordsmen except to get the swordsmith guild when I had too many florins anyway (hire and disband).

I concur with FactionHeir, the faction specific viking units will serve you well far into the game.