Green:
Kadilen - C is what Inari should have been, absolutely fantastic.
MN is better at rezzing but worse at healing than Heimdall. Paired with Sif she is fantastic on attacks (can’t see my defense but it hangs in just fine).
Tarlak is functionally covered with Miki and Wu
Blue:
Ariel #2 - Best healer in the game, good for wars, tossup between her or Skadi
Don’t see Krampus adding enough beyond what you already have via BK to justify him getting the nod.
Glenda could work next to an AoE or better yet, Skadi. ALL minions gone and deadly stack. Risk is raiding becomes boring … (is that a risk?)
Blue was your least obvious color for me.
Yellow:
Joon-C is a fighter! Extra stats make him almost robust but hits like a freakin truck and revives.
Leo is lower priority because of multiple G Jackals. I know they are flimsy but insane attack stat and easy to emblem.
Neith would be my second choice. Forum underrates her. I don’t have her but she can be tough to beat.
Red:
Marjana- You WILL get the costume and she is SO much better than Falcon I think she will have the biggest impact of the options you have.
Grazul tempts me, the protection for war depth sounds good.
Lady Loki can wait until you can have her firing at functionally fast mana (maybe you already can, depending on who gets the mana troops). If she can be made to fire in 9 tiles she jumps ahead of Grazul IMO.
Purple:
Onyx - Nuff said. Beast (granted Cobalt is >Beast but Onyx remains Beast)
These are my thoughts and are influenced by my preferences. I also LOVE Lady Loki and think Skadi is amazing (watching from afar as she graces other peoples’ teams).
At the end of the day effective and fun are not always the same and if in doubt I tend to opt for fun, sometimes knowingly sacrificing effectiveness.