You have way too many 50s compared to the small number of 60s, could've been further already if you'd used more of that energy to make level 60s... but anyway, it's a pretty great roster. 

I'd say the following are definite level 60s: FuShan, Foli, Skullcrown, Stag Knight, Skullcrusher. Some other viable candidates as well (Minaya, Scyl, Maneater, Mausoleum Mage, Frozen Banshee,...) but that first group seems like musts. Both Foli and Stag Knight are great all-round: arena, dungeons and CB. 

Also, I wouldn't worry too much about finishing nightmare, the last battle in particular is almost impossible to 3 star unless you use some cheesy unkillable tactics involving Paragon. 

thanks so are there some 50's and 40's i dont need and can use for food to rank up the others?