[quote=TJ]
This is another one of those "My preference is this, and I'm presenting my preference as fact so it should be done to my preference" threads. 
[/quote]
No. I am giving you feedback on the mod, which is the purpose of this forum.
@Jax
This is my reasoning for how I ranked the armors.
T-45d:
T-45d is the first functional model of power armor deigned by Wes-Tek. It is heavier, less durable, and more restrictive than later models of power armor. Statistically, it has 200 less health than "Black Devil" MKII APA, and incurs a higher agility penalty.
(Sources: Citadel terminal entries, FNV Dialogue (Elder McNamara). Fo3 and FNV gameplay, GECK statistics)
"Black Devil" APA MKII:
This version of APA MKII was deigned by the Enclave after they fled to the east coast. It is made entirely from lightweight composites. It is better at environmental protection than pre-war models, and is more durable. Statistically, it provides more radiation resistance and is more durable than T-45b, and incurs a lower agility penalty.
(Sources: Fo3 Dialogue (Casdin, BoS Scribes and Knights), Fo3 Gameplay, GECK)
Tesla MKII (DC):
Tesla armor is based off of pre-war blueprints designed by Nicola Tesla. This version of Tesla armor is based upon the "Black Devil" armor, and sports higher radiation resistance, and slightly higher protection. It is also much more durable and provides greater resistance to energy weapons. Statistically, it has 300 more health than normal "Black Devil" power armor, and provides 5 more points of radiation resistance, along with 10 points of energy resistance.
(Sources: Fo2 Notes, Fo3 Gameplay, GECK)
T-51b:
This model of power armor was the last version developed by Wes-Tek before the great war. It is made from a mix of metal and composite plates, and provides better radiation and damage protection than either "Black Devil" or T-45d power armor. The winterized version used in anchorage Alaska is slightly less protective.
(Sources: Fo1 Gameplay, Fo2 Gameplay, Fo2 Dialogue, Fo3 Gameplay, Fo3 Dialogue, FNV Gameplay, FNV Dialogue)
MKI APA:
This model of Adanced Power Armor was the first model of power armor to surpass the T-51b in protection. It was designed by Enclave Scientists after the great war, to give them a technological edge over the wasteland factions. It provides more radiation resistance and damage resistance than earlier models of power armor.
(Source: Fo2 Gameplay, Fo2 Dialogue, Fo2 Notes, *possibly FNV Gameplay)
MKII APA:
A direct upgrade from the MKI APA, this armor was also designed by the Enclave. It is more protective than the first version, and provides more radiation protection.This is the most advanced model of power armor. The only possible disadvantage is that is weights 5 pounds more than the first version.
(Source: Fo2 Gameplay, Fo2 Dialogue, Fo2 Notes, *possibly FNV Gameplay)
Hellfire PA: **
This power armor was designed by the Enclave on the east coast. It is the first version of east coast PA to equal the T-51b in defensive power. It is made from Duraframe, an alloy that provides a high resistance to fire damage.
(Sources: Fo3 Gameplay, Fo3 Dialogue, FNV Dialogue)
*The Remnants PA could be either MKI or MKII APA.
** Placed Incorrectly in my first chart. It is actually equal in power with T-51b, or slightly better.
P.S. I did not include charisma bonuses/penalties and faction effects in calculations. These are "human" responses to the armors and are irrelevant to thier defensive capabilities.
@TrickyVien If the BoS could not maintain their T-51b armors across the country, the enclave would likely face similar problems. And as for your second point, the lore is petty clear. The power armor seen in Fo3 is inferior to earlier models of APA. The Enclave lost all their research and manufacturing capacity at Navarro and had to rebuild from scratch. This is why Colonel Autumn considered the Hellfire Armor such a high priority.