That's true @tyrtaeus, if most of the party can hold their own in melee or at least have decent survivability there's less need for a defender to stop them reaching the back line. Although the unwavering mark feature would help keep melee attention focussed with the disadvantage on other adjacent targets that were less tough.
@JubalBreakbottlethe only warlord I was considering was the paragon, hence that feat. Also had my choice for next feat pretty set on mounted combatant - didn't take it at 1st level as couldn't start with a horse and figured it'd take 4 levels to get one. Appreciate the mechanical benefits of the paladin in terms of healing and utility, but my vision of Artanis doesn't have any magic, which is why I ruled that out. Plus I wanted to see his ideals tested, and that's harder to make interesting if his conviction is so strong it literally drives his class.
@Peacemongerhe does have an insane amount of hitpoints with an extra 3 per level on top of his d12 HD and Con. That's basically an extra wizard or sorcerer strapped to your character each level. Part of my issues was that I didn't think either would really change how I played Artanis to pick the most fun!
I think I'm probably leaning towards the warlord most again now, since it gives a few more different things to do in combat, and I've not played one before.