Alice or Gurptuk. I'd go with Alice. She's gonna help your account the most for dungeons 

You have several options, depending on what you want to do

1.) save ressources...in that case pick a rather low level cahracter and bring him up to 6*. Good choices would be Apothecary or Reliquary Tender. Both are rather strong rares in the beginning (especially Apothecary) -> you will save 4 4*-chicken and 5 5*-chicken if you choose Apo

Both rares are also rather easy to book

2.) If you want to bring a strong champ to level 60, Alice, Geomancer or Gurptuk...you will save 5 5* chicken. But consider that you also need to book them with the somewhat harder to get by epic or legendary books.

My goal is to go as deep in the dungeon as i can as fast as i can for the better drops and silver.