Maxout Sig for Sunspot or Domino?

I have 5* Domino and Sunspot. Which champ should I maxout the signatures? Where will the signature levels be more useful?

Comments

None of them

neither, save for someone that needs it more like omega or something

sunspot for prestige or save

Only for prestige otherwise save them.

Save them for someone like Omega Red or Colossus.

Niether