I was under the impression that a Dex paladin was more viable than a Str paladin, over all. If you're going sword and board, all martial one handed weapons do the same damage, d8. So you don't lose out choosing rapier over longsword or warhammer. Plus Dex adds to initiative, which is always good. The dex based skills can see a lot more use, like stealth. Plus most dex paladins do just fine with acrobatics if they don't take athletics. I believe Dex offers more skills than strength. Plus dex saves can tend to be more common than strength saves, depending on your DM.
Plus light armor plus dex bonus can get you just as good an AC as heavy armor. So Dex paladins tend to have more options with skills, can do equivalent damage, have better range attacks, have a better initiative bonus and can get a better score in a more common saving throw. Dex paladins aren't behind strength paladins at all.