Another army that started as an allied force (this happens a lot!) is this barbarian style Varangur mob.
Currently my most successful on the table, its still got lots of stuff to eventually get added. Given the theme, it also means there is scope to port over to Northern Alliance, depending exactly what’s in it.
Have a preference for slow and violent stuff (mainly cos I haven’t actually figured out what to do with cavalry & flyers).
Another force with a wide variety of stuff in it - Frostgrave barbarians are Sons (with old grenadier ogres); savage core cro magnons and warlord mastiffs the reavers/night raiders; krakon games & gw the trolls; nolzurs the devourers (and spiders aka tundra wolves) & poundland the cavern dwellers; direfang covered by space wolf stuff and riders kit bashed from panther riders and shieldwolf maiden bits - the panther from the former, crew from the latter and 4ground chariots make two further hordes; LotR army of the dead provide the fallen.