Do you have regret now rankup?
I have, just a few. Mine are 5* herc, doom, serpent, onslaught, fantman, fury because not so long after I got 6* version of them.
For 6* I have bishop and sinister, and then came 7* of them..
But, still pretty lucky, just herc that maxed, doom almost, he's in a low sig. So the thing is I try to avoid to invest into some champs that available as 7*. Except for serpent, I got him and dupe him so I can't hold to r2 him to help my bg deck. But since I also got 7* cosmic AG then I don't really want to maxed him now.
I guess that's kinda normal. Its a part of the game