Disagree with taking champs to 5* right now, I think we need to be focusing on one 6* at a time.
I would leave Warmaiden at 5* right now as she can function just fine there as a defense down champ and would prefer not taking her up to 6 unless we absolutely have to.
I think I'd take Toragi up to 6 first, as he's the best clan boss champ on the account who you can also use in Dragon at the very least.
Apothecary is a fine choice as well.
some future 6*s: Alure (S tier normal Fire Knight specialist), Skraank (good spider champ once you get towards 20 when HP burn strats get strong, is an OK CB champ) and likely Vogoth since he's a good all around defensive champ.