The Akil'zon fight has two major sources of damage: Static Discharge and the soaring eagles. The bit where you get thrown up in the air is annoying but causes no damage if you have your Light Feathers handy. And if you're getting hit by the storm, you're doing it wrong.
Static Discharge does 3500 damage on its initial hit. However, with three points in Playing With Fire, that's 3605 damage for me. The soaring eagles hit for 1600-1700 with my armor.
I look at the Akil'zon fight as having three phases:
1. Before the first storm, I DPS Akil'zon.
2. After the first storm, I play flak battery and attack the eagles.
3. When Akil'zon gets to 10% or so, I switch back to him.
For phase 1, Molten Armor would seem to be optimal. This is one of the two damage periods I get so I should make the most of it. Further, Mage Armor only increases the resistance by 18. Seems hardly worth it.
For phase 3, Molten Armor seems to be the better choice too. The other option would be Ice Armor to decrease the damage from the eagles. However, 10% will go by fairly quickly so the additional damage would be negated.
Phase 2 is the tricky one. Molten Armor damages the eagles when they come in and provides additional crit chance. Mage Armor provides an additional 18 resistance. And Ice Armor provides 645 armor and a possible slow.
Ice Armor would seem ideal but there are three questions:
1. How much additional mitigation does 645 armor provide?
2. Are the eagles affected by the chill effect of Ice Armor?
3. What percentage resistance is bestowed by 18 resistance?
#2 is an important question. Anything that can slow the birds down so they either attack less often or just stay in range of Fireball longer is a definite bonus. If #2 doesn't work, the answer should boil down to the expected difference in damage mitigated by Ice Armor vs. Mage Armor. (I expect Ice Armor to win this but I need more numbers.)
Given the penchant of the birds to attack one after the other, especially after you've taken damage from another source, packing Stamina gear on this fight seems to be a good idea. I've taken to wearing my PvP gear for this fight: It gives me additional Stamina and provides me with some amount of spell haste as a nice side effect.
I'm debating the usefulness of Gladiator's Silk Handguards here. The additional five yard range on Fire Blast would help some against the birds, I'm sure.