Agility on a tank

[Estu]

I just yesterday decided to remake my level 7 ogre warrior as a dwarven paladin (this is once I realized that all I'd ever be able to actively do would be essentially to taunt, bash, and kick). I've been contemplating what starting stats to go for and what stats to eventually get gear for, and one thing I never hear much of is Agility on a tank. Yet, it seems like the logical base stat to go for other than Stamina. Obviously taking hits is more important than DPSing, and I can aggro with spells as a paladin, so it seems like Strength and Dexterity are relatively low priorities. My question is, then, shouldn't Agility be the logical next stat to max out after Stamina (assuming, of course, that I'm also working on the actual AC on my gear, not just going for AGI at any cost)? At the low levels I've been playing, Agility seems to make a much bigger difference in AC than Stamina does in HP; two points of Stamina on my warrior only increased his HP by one point. What's the situation at higher levels?