I find that until you get well into the Heroic Age, it's best to always be trainingsvillagers. It allows you to have more resources and you can buildfaster (this helps when trying to take down lots of settlements). Aplus is that they only take one population "point", so it doesn't hurtto have loads of them. Having more villagers menas more resources,which means more troops, which means you can expand and win, too. Also: Don't be the Norse!