Champs that transcend rarity levels

Dexman1349

Are there any champs in the game who are so good they should be ranked up regardless of the rarity level you get (3* or higher).

For some context, I have over 8k prestige and my roster includes 15 champs with PI over 7k (5* R4, 6* R1 or higher) and include some big hitters like Domino, Blade and new Cap Marvel.

Synergies aside, would there be any 4* champ in the game I should rank up? If so, what content would they be helpful for (i.e. Variant, LOL, etc).

Aegon, Corvus, Ghost, other?

Psychoakuma

4* Scarlet Witch, SL and AA. Duped Voodoo too personally for me.

I use them in arena with my 5* R4's and R5's for fights to get past infinity streak (thanos teams) when running low on 5*s (and not needing to use R3 5*). I have 13 5* at R4 or above and 11 6* but still use those 4 heroes in featured arena for those fights when needed