Boss "Difficulty" Ranking List?

So, I attempted to Solo Uber Lab today and died at the very last moment of the fight... But it got me thinking about how difficult Uber Izaro was compared to other high-end content, and I thought it might be handy (Or at the very least sate my curiosity) to have a "Ranking list" of general Boss difficulty.


Noteworthy Bosses (I have likely missed some):

Merciless Malachai
Merciless Izaro (With and without Buffs)
The Pale Council
Atziri (Duo-Souls, Trio, Queen)
Uber Izaro (Uber Argus, Uber Izaro-No Buffs, Uber Izaro-Buffs)
Uber Atziri (Duo-Souls, Trio, Queen)
T14 Map Bosses
T15 Map Bosses



Obviously some will be much easier/harder for different build types, but, a rough list should be possible.

It has already been done. There is a ranking for maps here: http://pathofexile.gamepedia.com/Map

Not exactly what I'd call a difficulty list though, seems to be more a "Hassle" list since T1 Desert is rated the same as Uber Atziri.

HoGM is hardest and you didnt mention.

HoGM uses PvP rules, so, I don't really see it as comparable to any PvE content.

Plus I'm not sure I'd even consider it "Bosses", as such, either.

Impossible to make an accurate list, how hard is any depends on the build you run.

I had a colored map guide by difficulty of content similar to the wiki. Hot/cold colors are honestly way easier to notice than a number system. The boss difficulty do depend on your build... for example if you're armor/evasion/es/life/CI/Ranged/Melee and HC/SC etc. Phys damage kills evasion. Cold damage kills lowlife/CI without the right gear. Chaos damage kills most builds except CI. Then there's map mods that make some bosses nearly impossible depending on your build. Twinned, GMP, chain, turbo, extra damage, etc. You also have to worry about how lethality vs tankiness (endurance/dps race).

Never done: Vaal Temple, Plaza

Extremely hard:
Hall of the Grandmasters
Uber Atziri
Abaxoth (beyond)
T 15 maps
Uber Izaro
Excavation (T 13)
Vinktar Square (T 13)
Village Ruin (T 12)

Hard:
T 14 maps
Death and Taxes (T 10)
Wasteland (T 13)
Academy (T 11)
Poorjoy's (T 6)

Info in the wiki is pretty bad and inaccurate. And yes, certainly, boss difficulty could vary from build to build.
My own tier list, how I feel it (feel free to modify it, I didn't kill all these bosses yet):
1. The Shaper
2. Guardian of the Phoenix
3. Guardian of the Hydra
4. Guardian of the Minotaur
5. Guardian of the Chimera
6. Uber Atziri
7. Vaal Temple bosses
8. The Cursed King (Dark Forest)
9. The Eater of Souls (Core)
10. Atziri
11. The Pale Court
12. Ambrius (Colosseum)
13. Avatar of Thunder (Vinktar Square)
14. Avatar of Apocalypse (Death and Taxes)
15. The Infernal King (Abyss)
16. The Goddess (Plaza)
17. Izaro (Uber Labirinth)
18. Aulen Greychain (Springs)
19. Piety (Shrine)
20. Burtok (Necropolis)

I included only main bosses of corresponding maps. Obviously some maps are more difficult due to bonus bosses like Atziri trio, for example.
I excluded Hall of Grandmasters, because there are no real boss there, but I think it's most difficult encounter in the game.

I personally would put the pale council below uber izaro. That fight was never really a challenge to me, no matter what build I fought them with...

uber izaro easier than plaza boss and pale court? what? was the list made from standpoint of uber farmer build?