Favored Defense is hardly situational in module 9. It'll protect you versus 905 of what you'll face.
It has a few redeeming factors:
- +2 turn attempts
- +1 extra Lay on Hands
- +25% increased hate generation
- bonus to defensive aura
- Magic Circle
- Mass Shield of Faith
- Glorious Stand
- Divine Righteouness
Of course, the problem is that none of these truly is impressive.
Glorious Stand could have been quite good but it's too powerful for a short amount of time. To be more appealing, it should have a greater duration and reduced powers but that would go against the design goal of glorious Stand (ie short duration near invincibility) and would make of DoS a very back-loaded PrE.
Another thing that could have helped was Mass Shield of Faith, which saves an item, but my intimitank made Mineral II goggles which covers the +45 HP, Heavy Fortification and +5 Deflection all at once so there is no real item slot gain there.
The only possible advantage I see comes from Divine Righteousness, really.
While both Stalwart Defender and DoS gain +200% hate generation from defensive stance, paladins can gain hate generation thanks to Divine Righteousness, the DoS equipment set and DoS II which amounts to 287.5% hate generation for as long as we assume that positive bonus to hate generation apply the same as negative ones. That might be enough to grab aggro while not being crippled by the movement penalty from defensive stance.
That is a plus for the paladin if the movement penalty is a significant issue and the +4 AC is not a huge loss.
An interesting point about this is that, for a paladin in Defensive Stance to lose aggro, a character would have to deal 8.625 times more damage than the paladin which basically mean it is impossible for the paladin to ever lose aggro. That's something that all MMO developers want to avoid since allowing means that playing becomes very systematic.
Thus, I hope that my assumption is wrong and that it stacks differently.
Though, just an hypothetical situation underlines what I have been saying for a long time now: percentage-based aggro generating bonuses are short-sighted. Sooner or later, you'll hit a wall where tanks will be able to keep aggro all the time without any problem.