Zirda, the Dawnwaker -
Zacama, Primal Calamity for Naya value and control (you can still run normal ramp spells and dorks)
Gyruda, Doom of Depths - I still love the partner pair of
Sakashima of a Thousand Faces and
Tormod, the Desecrator and around 25-30 Clones and big boys.
Umori, the Collector -
Karador, Ghost Chieftain is pretty good, as most of the deck is already creatures.
Jegantha, the Wellspring - any 5c goodstuff pile, but I've actually seen a list for
Ramos, Dragon Engine/Jegantha charms deck. It looked fun to play, and offered a lot of flexibility.
Lurrus of the Dream-Den - I came across a
Bjorna, Nightfall Alchemist / Wernog, Rider's Champlain deck last week, and lost to the extremely low to the ground, grindy value deck. The deck was pretty insane, and won through
Time Sieve (mid, I know) and
Disciple of the Vault, combined with a lot of card advantage. Cool deck.
Obosh, the Preypiercer -
Karlach, Fury of Avernus +
Cultist of the Absolute + Obosh = any opponent dead through commander damage. fun.
Kaheera, the Orphanguard - need a list focusing on nightmares (with selesnya colors) or beasts. The latter could be cool if done right.
Keruga, the Macrosage - powerful for
Imoti, Celebrant of Bounty, Yarok, and other heavy Simic decks with obnoxious amounts of ramp.
and for the other 2...
These ones are problematic even if allowed. Lutri is good in any deck with spells of MV 5+ (extra turns, big splashy stuff, etc.) and already banned, so good riddance. Yorion, on the other hand, would be an auto-include in any
blink deck (he already is in maindeck) and provide lots of value, guaranteed. The problem with these two is that their restrictions are not as potent, so they fit in anywhere, and
defeat the purpose of companions as an incentive for creative deckbuilding. Enough said, need to brew a Zacama/Zirda naya control deck now...