Mutant Rank Up - 5* or 6*?

Avengerboy99

I have Doom and Quake as R5 and now I'm looking to get one of my mutants to that level. Please let me know which is the better option.

SpideyFunko

although personally I’d go prof x, apocalypse is a beast. Great damage, horseman ability, synergy fiesta, etc etc.