Possible Combinations

Originally when I was thinking about the interaction of classes and power sources, I was thinking that each one would have a favored attribute regarding prime and high score. So, a fighter type would want to have STR prime and a high STR score. This is how "traditional" D&D works -- fighters have always been rewarded for having high strength, and its foolish in most cases to select something else as more important. The problem with this is that it prevents a meaningful choice, and it allows an opportunity to choose to suck (i.e., you could make a fighter with poor STR, even though its probably not a good idea and will mechanically punish you).

I prefer to broaden the class archetypes and make differentiation by key stats a meaningful choice. For example, say you can select a "power source" (class) and a prime stat. You could get combinations like:

MARTIAL
Body Prime: Traditional Fighter, possibly barbarian
Agility Prime: Swashbuckler ("rogue," if you must go there)
Heart Prime: Skald, warlord

ARCANE
Body Prime: Swordmage, Spellsword, Eldritch Knight
Agility Prime: Traditional pointy-hat wizard
Heart Prime: Bards, possibly sorcerers

DIVINE
Body Prime: Paladins
Agility Prime: Monks
Heart Prime: Traditional cleric

You've now given the player a significant and interesting choice at character creation. By picking from two lists of 3, you get 9 different combinations. Indeed, if you allow for a numerical 3-18 score in the attribute primarily used for derived statistics, a prime used for giving bonuses to proactive activities, and a power source, then there are now 3 sub-variations for each archetype! For example, you could have a Body-Prime Divine character who chooses to put a high score in Heart (so that he can hire a large entourage) instead of Body -- this may prevent him from being able to carry Plate Mail but its an interesting and viable tradeoff.