I was going to try out the 27 color commander challenge, but I decided that not every color combo was necessarily good as of this posting, so here are the Commander's participating in my list

Tribal

General Tazri-Allies

Tajic, Blade of the Legion-Humans/Knights

Sliver Overlord-Slivers

Olivia Voldaren-Vampires

Scion of the Ur-Dragon-Dragons

Ezuri, Renegade Leader-Elves

Wort, Boggart Auntie-Goblins

Gisa and Geralf-Zombies

Rakdos the Defiler-Demons

Derevi, Empyrial Tactician-Wizards

Progenitus-Gods, Titans, Planeswalkers, the usual

Progenitus-Eldrazi(Unless there is a Five color eldrazi that is legendary)

Child of Alara-Angels

Brago, King Eternal-Spirits

Sygg, River Guide-Merfolk

Kaseto, Orochi Archmage-Snakes

Mono Colored

Talrand, Sky Summoner(Blue shenanigans)

Kemba, Kha Regent

Daretti

Ravnica Guilds(Two Color Commanders)

Trostani, Selesnya's Voice

Omnath, Locus of Rage(Red Green Lands Deck)

Lazav, Dimir Mastermind(Mill, might make some other list though)

Noyan Dar, Roil Shaper , Bruna, Light of Alabaster

Teysa, Orzhov Scion

The Gitrog Monster , Meren of Clan Nel Toth

Melek, Izzet Paragon

Shards and Wedges

Oloro, Ageless Ascetic , Sen Triplets

Doran, the Siege Tower . Ghave, Guru of Spores , Karador, Ghost Chieftain

Phelddagrif , Rafiq of the Many , Roon of the Hidden Realm

Marath, Will of the Wild , Mayael the Anima

Prossh, Skyraider of Kher

Marchesa, the Black Rose

Animar, Soul of Elements

Zurgo Helmsmasher , Kaalia of the Vast

The Mimeoplasm , Sidisi, Brood Tyrant

Narset, Enlightened Master

Tier's(Based on thegigibeast's list)

Tier 5: Rakdos, Tajic, Phelddagrif

Tier 4: Kaseto, Lazav, Mayel, Olivia, Trostani, Wort, Sygg

Tier 3: Bruna, Doran, Ezuri, General Tazri, Gisa and Geralf, Kemba, Noyan Dar, Omanth(Both), Progenitus, Rafiq, Sen Triplets, Sliver Overlord, Talrand, Teysa, Zurgo

Tier 2: Child of Alara, Daretti, Ghave, Kaalia, Marath, Marchesa, Melek, Meren, Oloro, Roon, Sidisi, Gitrog

Tier 1: Animar, Brago, Derevi, Karador, Narset, Prossh, Scion, Mimeoplasm

Four Color is being held off on right now, colorless will technically be the Eldrazi(Devoid I guess?), and I have the missing guilds, wedges, shards, etc. in the Tribal section. Some of these have more than one commander because they do very different things, and some of them might actually be pretty fun to play, such as the Gitrog Monster.