the first thing you're going to want to do is bring a champion to 60 who is able to run stage 12-3 on brutal campaign solo. i would suggest ronda for that role. once you've done that, run 12-3 with her and three "food" champions (champs intended to rank up other champions) until they hit rank 5, rinse, and repeat. grinding on 12-3 is going to be the fastest way for you to rank up your champions.
in regard to your champions, ronda should be your first 60, followed by deacon. he's an amazing champion and will help you in just about every area of the game. apothecary is also excellent and frozen banshee should serve you well for clan boss and dragon's lair at the moment. armiger should be put on the back burner; he'll be an excellent champion down the road, but he's not much use to you at the moment. galek and warmaiden likely won't be of much use to you. galek i'd hang on to just to fill out your team but i wouldn't bother investing in him any further. you'll eventually need a copy of warmaiden to fuse justicar so you may want to keep her on hand for that; otherwise you can go ahead and use her as food.
i would urge you to keep shaman and jizoh. you generally want to hang on to a copy of every epic and legendary you get, even if you dont see an immediate use for them.