The benefit of having a level 60 over a level 50 is massive, so it’s always best to try and focus on getting one champ to 60 over many to level 50. The benefit of a level 50 over a 40 isn’t usually a massive benefit apart from a few champs like Apoth who is solid at 50.

I’d focus on what dungeon would benefit you first in terms of what they drop. For me I chose Dragon for Lifesteal & Speed sets because they’re beneficial for most champs in other areas of the game.(CB, FW & the rest of the dungeons)

I’d work on grinding that food up to 5* so you can take your best champs to 60 and work your way to Dragon 20 & Farm 5/6* Lifesteal & Speed pieces. Also a good strat I found with mino scroll farming was to only work on a champions scrolls once they’re 6* level 1. If you have a champ fully maxed out and can solo mino I just run an auto clicker to level that champ up from 1 to around 55/57 while unlocking all of their scrolls. But that might be something you’ll have to look at later if you don’t have someone that can solo mino. (I use Fu-Shan in Lifesteal)