Paladins

Paladins serve as divinely charged warriors who bolster and safeguard their allies (or strike terror into their foes).
Crown paladins aren’t terribly common or uncommon, but for obvious reasons are highly favored by rulers the world over. Eager state sponsorship ensures that paladins who take this oath are always well provided for.
Conquest paladins serve as terrifying vanguards, opening the way for soldiers behind them and ruthlessly suppressing their foes. Martial champions extraordinaire, their chapters tend to be small, as fierce competition sets in and few outside this order are particularly interested in their continued existence.
Redemption paladins are the rarest, as their pacifist ideals are lofty but (in the eyes of many) impractical. Though beloved by celestials and goodly churches, Redemption paladins are often humble without having a choice in the matter.
Ancients paladins hail mostly from older races and those who are somewhat chaotic at heart. Dedicated to preserving joy at the wonder of the world and their free spirited brethren, these paladins get along extremely well with the right sort of community.
Devotion paladins are the archetypal holy warrior, often dedicated to a good church or civilization. All have a philosophy or deity to which they adhere and that supplements their oath. Their chapters are usually backed by an organized religion.
Vengeance paladins rarely form organized chapters, but when they do it’s always for a grim purpose. Invariably formed in the crucible of personal tragedy, these individualists still recognize the benefit to working as a group.