What Should I Focus On?

I am currently in League 14 and I’m having trouble deciding what I should be prioritizing at the moment.

I have at least 1 male and 1 female character at 4sb in each class. Highest characters star wise are a 4ss Sid and 4sg PH Brie.

I can’t decide if my current focus should be to get more characters to 4sg in order to keep progressing to League 15, or if I should focus on getting characters with useful trainer abilities leveled up high enough to maximizing their trainer abilities.

What should I be prioritizing?