Since it’s for war, big determinant is tank color.
Idk about lower tiers but Heimy tank is pretty ineffective even with emblems. Think about MN or Alby tank and that’s same reasoning, too slow and easily countered.
All three best in left wing for latter stages of battle.
I’d ascend Vela, then toss up between Magni and Fenrir. Magni first if you get his costume.
I’d ascend a second Marjana over Khagen, Elena or Azlar. Maybe Azlar if you get his costume but Marjana would still be on your defense.
Viv or wait for yellow, best bet is costume Joon or when Poseiden is featured in Atlantis.
So save Khagen, Elena, Ranvir, Leo for HA.