Krissy Von Doom
Restricted
It goes without saying that the One Above All and The Living Tribunal own the top two slots as they oversee the whole multiverse hence they're the most important two in the cosmic hierarchy. Admittedly, I don't know anything about the "Heart of the Universe" but how does this give you more power than the Living Tribunal if it's just "Universe" when the Living Tribunal judges the whole Multiverse?
Needless to say, the wielder of the complete set of Infinity Gems comes just below the Living Tribunal, however I'm not talking in terms of power, I'm speaking in terms of cosmic "standing" and importance - not wanting to get into the whole LT vs Infinity Gauntlet argument here.
Right under the gems are Eternity, his "other side of the coin" Infinity, and their universal counterparts, Death and Oblivion. These four are seen "discussing" matters as equals in the pages of Quasar after the whole Maelstrom storyline hence they're equals in universal importance, though their actual powers may vary.
Some would argue that Galactus is either on equal footing with Death and Eternity or just a step below them because he determines the universal balance, I wouldn't argue with either point. Although normally his power is dwarfed by the big four just above him, his existence is nonetheless crucial to the universe. I'd put the way he addressed the cosmic beings in Infinity Gauntlet as an important point - when the LT didn't want to get involved, Eternity left, who spoke to the assemblage as the next in line to lead? This guy.
The universal scientists, the Celestials, are next in line, if not only in terms of power and numbers. And, somewhat synonymous with the Celestials now, is Franklin Richards, not because of cosmic significance but because of the power he wields. Just below the Celestials are Lord Chaos and Master Order.
Just a few quick points:
I think The Stranger, although powerful and mysterious, doesn't really hold any cosmic significance. He's "only" the collective people of Gigantus, I believe similar to the Uni Mind and when the Asgardians merged into the Destroyer Armour. Powerful, yes, Important, not so much. On the same boat is Tyrant.
The Skyfathers and higher mystic beings (Mephisto, Dormammu, Cytorrak, Vishanti) are equal, I may be wrong though
Natural universal forces are equal - Uni power, Phoenix Force, Starbrand, I may be contracticting my first list
Beings chosen by higher cosmic beings are equal - Heralds (by Galactus), Thanos (by Death), Drax (by Kronos), Protectors of the Universe