Let’s go…
Purple:
I’d finish Proteus for challenges etc., I like him very much. Because I already have Rigard and Sabina maxed, I’d start with Sartana and will see if I can get Rigard’s costume, otherwise I’d max the second Sabina, I like to have at least 2 healers for each war team. Maybe I’d feed Renfeld
Yellow:
I would level Vivica or another Li Xiu and then 2 times her costume. Melia would be a nice addition in between for challenge events, she and Brienne make the others hit so much harder.
Blue:
Not so easy, I think Magni would be a good choice for a 5*. I have 3 maxed Kirils and the next thing I do is Sonya’s costume and a second Sonya with costume. But you don’t have her costume…
Maybe I’d max a Boril, he can be helpful in some situations. And I’d put Grimm in the line to level. Maybe Gunnar’s costume and a second with costume when the mats are running out…more Gatos can also be good for events.
Green:
Uhh. Elkanen, Brienne’s costume, second Mnesseus, Little John, I think. Or hoping to get a better green 5* and work on Melendor 2 in hope of getting his costume someday. I’d feed the 2nd Muggy, I see no use…
Red:
Azlar, Kelile, maybe 2nd Hawkmoon costume and Colen. I won’t max Khagan or Sumitomo…
You’d have a nice 3-2 stack in purple and blue with Kiril, Rigard, Grimm (when he’s maxed), Proteus, Triton or Sonya and the other way round with Sabina, a second Kiril, Tiburtus, Triton/Sonya and Jabbar or later Sartana.
In other colors it’s not so easy for me to decide. And you asked for def. I like one healer and some fast snipers. So I’d go with Li Xiu as tank and:
Caedmon/(Elkanen(?) - Kiril - Li Xiu (with emblems) - Sartana (once maxed)/Proteus(?) - Scarlett
or for the moment
Kiril - Tiburtus - Li Xiu - Caedmon - Scarlett
Or with Melendor:
Melendor - Tiburtus - Li Xiu - Sonya - Scarlett
Or with no healer at all and use Caedmon instead.
When a Boril is maxed, you can also use him as tank and Li Xiu as flank then.