Rank up question

Amarrite

So, I only have one really good 5* (stealth spidey at R3) out of the eight our so I have. All unduped and at rank two or so with the exception of Spidey and Annhilus. My question is should I be ranking my good 4* champions to rank four or five, or concentrate on the 5*. I have some catalyst I have been saving up for my last quest to get uncollected. I'm just not sure what way would be more beneficial in the long run. ranking up the 4*s or saving them for the 5*s? I have some decent 4* champs I have been collecting from the 4* arenas that are duped just sitting at rank one.