My line up for blue: Magni, Arthur. (and Grimm and Sonya)
Would you go for Misandra, Alasie or Aegir?
My line up for dark: Panther and Sartana (and all purple 4 except sabina and tiburtus)
Would you go for Aeron or Khiona?
Rest 5* in tier 4:
Green: Evelyn, Zeline, Lianna
Yellow: Delilah, Joon, Rana (vivica at 3-70)
Red: GM, Zimkitha, Marjana
Put your own questions down 
Alasie for blue. Aegir is an iffy hero, at best; Misandra hits less hard than Alasie and is less impactful in raids and wars.
Khiona for purple. This is less clear-cut, because 5* healers are a valuable add, but with Panther, Khiona would be a great add for her purple heal and nearby attack buff. You don’t need to heal if you can kill everything quickly, and that’s what Panther + Khiona + Sartana will do (especially against yellow tanks – that’s a Guin-killing machine there).
How would these three look paired WITH Guin–asking for a friend…
For blue you have a sniper, elemental down and defense down.
Your next should be a hero with high tile damage. The current queen is Isarnia who can also replace Grimm as def down.
A healer would be nice but only 5* Aegir has any healing , if you can call it that. I think he is better than people think but I still wouldn’t make him a priority. Kiril has to hold in there until a better 5* is introduced.