A GRID: I MUST FILL IT!!
But not a law/chaos, good/evil 2D grid. We can throw race in there! ....and 'power source equivalent'!!
This isn't sarcasm, this is what I want to be able to do (and enjoy doing). I'm not saying there should/must be a unique 'lawful evil arcane half-orc knight' subclass, that leads to poorly made classes filling a 'bad idea' slot in the grid, I'm just saying if a combination has a flavorful classical archetype champion (lawful dwarf, martial chaotic, good elven alchemist champion) it would be cool if they could be unique subclass based on the paladin. I see three paladins, and I want to make an army of paladin choices, and fill in the interesting points with my ideas, and leave blanks that can be filled by players with good ideas. But this is perhaps off topic.
ON TOPIC: I'm okay with the default sub-class having the same name as the over-name (Paladin). I'm also fine with it being Knight. Champion IS a good/correct over-name, but I don't like it, though I can't give a good reason, so its likely just a personal hang up. (I remember the "Champion of Torm" prestige class in the 'hordes of the underdark' neverwinter nights expasion and how it was such a bad choice to take it for my character, that's probably my problem.)
I hope I love the "green knight" warden, it's right up my alley, but I agree that 'neutral is not nature', and hope that 'grey knights' of a 'civilized' flavor appear, likely with some alignment overlap (The Grid! THE GRID!!!!).
Cavalier doesn't ring "Lawfully good Holy knight" to me. Again this probably is related to my first d&d experience with the cavalier class in "baldurs gate II", which was a paladin kit focused on going toe-to-toe with demons and dragons (to the extent that they could not physically equip ranged weapons). This combined with the common phrase "Cavalier Attitude" (marked by lofty disregard of others' interests, rights, or feelings; given to airy dismissal of things worthy of attention.) caused me to classify the cavalier as a name for a fearless knight with probably more sword than sense. I'm not saying this is what it means or should mean to everyone, but this is my affection for it, and I really wish it was how it manifested in D&D. I'm learning to live with it. Still, my own fantasies aside, cavalier is not an obvious choice for a traditional paladin, nor a good one, IMHO.
Obviously the Blackguard is the evil knight. I feel that for Lawful evil it should be pronounced 'BLACK-guard', for neautral evil 'Black(g)-heart', and for chaotic evil use the 'Blaggard' pronouncination.