I got like 35 norse bodyguards right now, who cost like 1400 dollars just for their final upgrade alone (not including all the upgrades til then), and they are just absolutely savage in my armies (expensive as ♥♥♥♥ though, so i keep them in my castles and only grab them for when im going to conquer). I'm mostly sticking with the viking armies myself, just focusing on badass infantry units. I found that nords give the best foot soldiers (not archers, id ignore them with the norse guys), it seems that the english give the best calvary units, and i have spent barely time on ireland and dont know too much about the scots, but id assume that theyd both have superior skirmisher units, though i could be wrong. Im just learning most of whats good or not in viking conquest right now too. Problem is in late game everybody got max tier units, and the generic merc guys only advance up to one or two tiers less than specialized units (like nord veteran/nobles). Like you said, they are good for filling in right now and being decent fighters. The merc/bandits are good for early to mid game.
