banshee is a beast in clan boss definitely get her to 6 star to help push your damage up, im no big hitter just have found a sweet champ combo that helps me 2 star top chest daily which in my clan with us wiping daily means 2x chances of legendary books sacred shards etc

banshees my damage dealer and can carry that role easily with her A3 and A1 abilities, you have some solid champs in that screenshot with coffin smasher, apothecary, cupidous etc but I personally would do banshee if it was me and you were looking at progressing with your farming - checkout ayumilove its a website that gives tips on where champs are best suited to gear they should have and the masteries they recommend for them.  

towers a beast  with block damage for arena, but id personally If I was you start farming hard in minitors for scrolls as soon as you get to warmaster in scrolls your damage in clan boss with jump easy 3 - 5 mil

clan boss is a great way to progress with the daily rewards its just hard to grind out all those scrolls especially early on when all 5 champs steal all the scrolls, once you have  4 of the 5 fully scrolled out farming scrolls with just one champ needing them is so much faster but til then itll take you a while unless you have heap of gems then you could buy all the scrolls for that champ for 800 gems from memory