How you choose to promote your villagers into can have a great effect on how your specific journey plays out. Many villagers have only one or two promotion options that are more helpful in the long run compared to others, which makes choosing even more crucial. Choosing poorly can result in a much harder game than it needs to be, and you won't be able to change your mind after picking their promotions.
If you're looking for the best possible setup with thinking too much about things, then try making Atlas and Gray Mercenaries, Faye a Cleric, Tobin and Archer, and Kliff a Mage.