if I were to change something about maudlin's which I think is best of above:
UEF - unite the galaxy using powerful conventional weapons and defenses with durable units
Cybran - liberate the galaxy using stealth and surprise attacks with highly versatile and fast units
Aeon - cleanse the galaxy with specialized units that excel at a single role but depend on cover of others
Seraphim - annihilate the galaxy with strong alien units with unique and advanced weaponry
EDIT: no point describing the looks of units because you can just show them
uh ok