I agree with Yerba; of all the classes, Paladins have the easiest time getting maxed resists. Um'd Hoz (72) + low Mara (23) + quests (30) + avg. anni (15) + avg. torch (15) = 155% to all. Even the worst Fort will max you out at 75%all in Hell. With a 35% Metalgrid, P res torch, P res anni, you can have 75% to all resists in Hell with no resists from your helm or armor, so you get the idea.
Try to find a way to replace the huge damage, life, and defense boost Fortitude provides and you'll see that Fortitude is far superior. I even like using Prudence in a glitched eth armor better than CoH. Zero repair cost and not getting hit (insane defense) is nice. That's what I use on my PvM Zealot most of the time (including Ubers). I find that with his gear I don't miss the extra damage and it's fun to be different.