Abstruse
Legend
You mentioned that PALADINS do not have any variations at all?
Please read Pathfinder's Advanced Player's Guide, Ultimate Combat, and Ultimate Magic splat books.
You will find Paladin's having the default archetype,
then the following new archetypes:
APG: Divine Defender, Hospitaler, Sacred Servant,
Shining Knight, Undead Scourge, and Warrior of the
Holy Light. This section also includes rules for an
alternate version of the paladin class, the antipaladin.
Ultimate Combat: DIVINE HUNTER (this is an archer paladin), EMPYREAL KNIGHT (a celestial servant), HOLY GUN (a gun paladin), HOLY TACTICIAN ( a leader based paladin), KNIGHT OF THE SEPULCHER (anti-paladin variant), SACRED SHIELD ( a shield specialist),
Ultimate Magic: Oathbound Paladin (comes with around 10 oaths)
This is why i really really like what Paizo did here. But it doesn't mean i'm a Pathfinder player, because I just started this one just to try it out. I am a hardcore 4e player.
p.s. you should really read the books
My Pathfinder game is currently in Ravenloft. Last thing I want to read about is paladins. And I'm immediately dismissing two of those because one involves guns and the other is an "anti-paladin" which I've always thought the stupidest idea in a game world with a polythieist pantheon.
Now let's go over the others. Divine Defender, Hospitaler, Sacred Servant,
Shining Knight, Undead Scourge, Warrior of the
Holy Light and Sacred Shield. That really sounds to me like six different names for the same exact archetype - holy knight in shining armor. Need better than that.
Holy Tactician: Oh, so a divine character who stands behind the front lines offering tactical advice and support along with magical healing and divine spells? Sounds almost like a cleric.
Empyreal Knight: So an even holier holy knight in shining armor? Also, the name sounds funny. "Impy-real". Say it out loud with a straight face, I dare you.
Oathbound Paladin: (Looks like the Paladin version of the monk vows. Completely wasted mechanic, that. Anyway...) Doesn't change the fact that the paladin is just a holy knight in shining armor. It's a min/maxer tool to gain a bonus for what they should've been roleplaying in the first place.
So out of all those variations, the only one you gave me that doesn't fit the standard of "Heavy armor, melee fighter, casts divine spells" (which clerics are all capable of as well) is the archer...which clerics are capable of as well. Hell, I've played enough clerics and wizards in 3rd Edition that I never want to see another crossbow as long as I friggin' live.
Sorry, but that's not enough to justify an entire class in my opinion. Every single variation can be done just as well if not better by some use of the established cleric or fighter class with the addition of themes and/or multiclassing.
And it still doesn't address the issue of D&D being set typically in a world with multiple different deities of multiple different personalities with all of whom being the type to take advantage of creating their own divine warriors. A god like Bahamut would have warrior-priests similar to the classic paladin for all his clerics. Show me a paladin class that would work just as well for a follower of Melora, Avandra, and Pelor as they would for Bahamut, Lolth, or Kord.