Sanctified Mind out of Lords of Madness is actually a pretty good option to at least dip; full BAB, good Fort and Will, 4/5ths casting (or manifesting), some solid Charisma based class features (Partition Mind!), and the only part that sucks are the entry requirements; 2 of Knowledge (Dungeoneering), Knowledge (Psionics) and Sense Motive, as well as at least 1 power point. If you're using Magic-Psionics Transparency, it's actually pretty potent with its Disrupting Blow ability which could knock out SLAs/PLAs for a few turns.
Pious Templar from Complete Divine is another dip worthy option, with full BAB, good Fort and Will, and grants Mettle for a single level. It sucks on the grounds of feats you need Weapon Focus (not fun) and then True Believer, which the latter could be really useful. It also has its own spellcasting progression, but aside from Mettle early on, its not that special.
Hellreaver from the Fiendish Codex II is a really active, almost Tome of Battle style paladin-esque prestige class. Its abilities might not be show stopping, but they're flavorful and are actually really versatile. It is built almost entirely around fighting evil alignment enemies, but it combos well with the Chaotic Good paladin, or any of the variant paladins from Dragon Magazine that get something other than Aura of Courage. It also gives you more to do than swing your weapon at things and hope your Smite Evil lands. Has full BAB, good Will, Mettle and its own point based action economy using free, immediate and swift actions.
Those are just some good things to look into if you really want to go with the paladin ideal.