First of all, I am incredibly biased when it comes to paladins. I think they are freaking cool.
Unlike other classes which can walk the line between light and dark, the one thing you can count on is that the paladins are the good guys. They do the right thing.
Need an NPC the players can trust? Add paladin. Need them to know the situation is dire? Add paladin. Do they want a decent western from the late 50s? Suggest “Have Gun, Will Travel”.
That’s a Paladin joke.
As far as a class, the paladin is basically supposed to be a cleric/fighter hybrid, with neither of the focus of either. As intended, it functions just fine. As far as average power level, it’s been relegated to the lowest tier by the D&D community, even behind the fighter.
It’s unfocus that is it’s greatest liability. It doesn’t have the skill points to be good at social encounters, and it doesn’t have the feat to exceed at melee, and it’s spellcasting is downright rudimentary.
The question would be, what would be the best thing to give it to make it better? Pathfinder’s solution was to dramatically increase the power level of the smite ability, and I approve of that.
Another option would be to give it an extra skill point per level, or an additional bonus Exalted feat at first level. Of course, simply giving the paladin the benefit of the Nymph’s Kiss (BOeD) feat (without the required relationship) would actually fulfil both suggestions perfectly.
Another major complaint about the paladin is the horse. On adventures in dungeons, a heavy lancer isn’t going to see much time on the table. For that I suggest the ACFs found in Dragon 358. It swaps the horse for a magic weapon granted by the celestials that slowly grows with the player. Its a favorite of mine. Last time I got to play I got myself a Thor inspired hammer!
One of the most common complaint about paladins (by players at least) is the oath. They can’t break the oath or get massively kicked in the teeth by karma. This is complaint is not valid, really. It just makes the player actually play a damn hero instead of the usual selfish merc bastards they usually play.
In fact, broadening the paladin oaths to include other alignments is a major complaint of mine and did the class a great disservice. Now, instead of a beacon of awesome in an otherwise bleak world, “alternate” paladins are just neopolitan fighters, yet another meaningless gish build. I hate that. It doesn’t happen at my games.
The oath itself isn’t a drawback. It’s what makes the class special! None of the other classes have such a strong roleplaying guide baked right in.
One thing I would homebrew though. There are several feats released in the “Complete” series of books that encourage multiclassing in otherwise difficult classes like the paladin and monk. I would create one that allows multiclassing between the Paladin and Marshal class. It would ease some of the troubles the paladin has with being the “face” of the group, and solidify his role as the center of the party by granting him auras.
My prototype feat…
Prerequisites: Ability to smite evil, ability to manifest a Major Aura
Benefit: both Marshal and Paladin levels stack for the purpose of calculating Smite, Lay on Hands, and the power of any manifested Auras, and allows multiclassing freely between the two classes.
That makes the feat takeable at level 3 by a Marshal2/Paladin1. It’s probably a very weak option, with both classes being very feat starved to begin with, but I like it.