Do you unlock kingdoms as fast as you can or finish their quests before unlocking a new kingdom?
There’s no harm in unlocking them. That way if you feel stuck in one quest you can try a different one.
Unlock all of them as soon as possible for the banners, gold income, and tributes
It depends on how you’re playing but I think, in theory, unlocking them all is “better”.
My hypothesis is “having more kingdoms available to tribute” is better than “having more kingdoms with quests finished.”
In the end though, unless you play at a glacial pace, within a few months you’ll be making so much gold daily this tiny difference won’t matter, so do which one is fun!
I finish all of a kingdom’s quests and challenges before moving onto a new kingdom. I think the more kingdoms you unlock, the more kingdoms are revealed. However, there are certain areas that are only accessible if you complete the linked kingdom’s quests such as the underworld.
Thanks for the help, everyone! I try doing one at a time to see how it goes.