What are the easiest CB To grind?

Honestly idek what I'm trying to say,but I'm basically saying this because some cbs are considerably easier to grind than others.

Not only that,i have grinded a few medals from the serious battles with kubo + leo giving me 100% points

The most boring cb to grind is probably the counter battle because it uses an actual party

Ofc if you're a whale and have every character maxed this wouldn't be a problem,you would get all the score bonuses