Long-time Tankadin here with new 2.3 gear and a need to switch around some enchantments. I now have 15k health unbuffed, over 17k armor (giving me 62.64% physical damage mitigation), and am still able to generate more threat than Rogues and Moonkins that just don't care (well, usually anyway).
So I was thinking about replacing the 'ole +2% threat enchant on my gloves. I can typically do enough burst threat at the start of any major fight (Avenger's Shield > Consecrate > Holy Shield > Judgement of Righteousness > Seal of Righteousness > Repeat for steps 2-5 three times) to be able to switch over to Seal of Vengeance and get my own 5 'sunders' up on the boss and hold them forever. So the question is +Armor or +Stamina?, or should I stick with +2% Threat?
I know more Stamina is always a great thing. And with my own +16% to Stamina talent buff and Kings, that +10 Stamina actually equates to probably +140 health, but I also know that, with 490 Defense and 102.4% Uncrushability, stacking Armor to increase my total effective health is also vitally important.
So for overall increase of Effective Health, what is better? +140 Health or +240 Armor?
Don't forget 15 agility. I'm pretty sure it's about 0.5% dodge. Armor or HP for your EH gloves, 15 agil for avoidance, and threat for your threat gloves (weapon skill!!).
Edit: Punctuation is gud. Also, if your armor is good but your hp needs a bit of work, go with the HP patch. If your hp is good, but you are using a few pieces of gear that are behind on ilvl, use armor.
In terms of effective health, +240 armor and +10 stamina should be largely a wash for you (with your current armor, including devotion aura, you'd break even somewhere around 17500 health).
In short, I'd suggest to grab what you need more. Personally, I'll be going for the +10 stamina (even though it is slightly less beneficial for me), because my armor and effective health is generally fine to handle the physical attacks of most everything I'm tanking; my current focus is on surviving better when my armor doesn't help me (such as against Nalorakk's bleeds). I'll probably put the +2% threat enchant on a different pair of gloves, too.