can you post a screenshot of your whole collection? the answer really depends on who else you have.

Sure. 

i

before any of the three you mentioned, you should level up deacon. he's an absolutely amazing champion and will help you in pretty much every area of the game.

Deacon is a great choice. Nothing wrong with a speed lead, a TM controller and an AoE Dec Def all rolled into one champ.

Plus he's an epic so you'll actually have a few books for him hopefully.

Okay, understood, after Deacon can you recommend me wich one I should level up?

Concentrate on Deacon first...perhaps you will have some more champions by the time Deacon is finished..

I'd say a healer, if you have a good one by then. What you need right now is a good well-balanced team for progression. Forget about flashy legendaries for now, they are a pain to book and not necessary at this stage. 

Actually I do not think a healer is important. There is a fully ascended Salad who can chuck out Leech...Deacon , 1 Kael, Ronda and Zhavia should carry you for quite some levels

Okay, thanks for the advices, I tought I had to level up legendary ones first but I was wrong

It will likely be Ronda. She's a decent campaign farmer, smacks in Arena, can really help you jam out dungeons. In a referral alt I had her easily solo farming Dragon 11 in the starter the lifesteal gear, and she was able to push much higher with a team, rather than 4 unleveled food champs.