ISO in 4*'s or 2*'s?

Need help folks… I recently sold a bunch of champed 2 stars to champ my first 4* (Thoress).

I have about 10 or more covers for most 4*'s. Should I invest ISO in them .. or should I focus on investing ISO on re-champing my 2*s?

Help and guidance would be much much appreciated!

Thanks!

Depends of your overall roster hard to say without knowing that

are you satisfied with your pvp performance or not? if you’re satisfied, complete the lower end you’d like to complete (I’m in the middle of doing this right now). if not, and you have top tier 4s ready, do those.