IMO,…
Yellow: 2nd Jackal, 2nd Miss, Hu Tao
Purple: C Cat (the only fast 4* purple outside Gafar), good for bloody battle tournament
Green: Melendor + Costume, Caedmon
Blue: Sonya + Costume, 2nd Sonya if we have, then Boril
Red: Sumitomo is not bad after buff. Gormek is also good for war, I think Colen will be redunant if you already have 2x Sumle.
Mana Troop
Yellow: priority 2x troop to level 11 for 2x Jackal
Purple: level 5 for Rigard and or Tiburtus costume
Red: level 5 for Boldtusk costume
Here is Troop summirized:
Original by @flyingsolow here.