Mostly: no. There will be situations in Hard Doom Tower Secret Rooms and Sintranos stages down the line (but not very important now) that you may want a few of them at 60. There may also be some Faction Wars stages between 18-21 that you may need a select few if you're close to finishing off Lydia, but my gut says this is less of a thing than it was a few years ago.

Would you mind posting your roster in screenshot form? Curious to see what you're working with and will provide an opportunity to maybe pick a few rares out.

Short answer: no.

There are a handful of rares who are definitely worth keeping and fully building. Also you want to bear in mind there are certain doom tower secret rooms that can only use rares.

Also, it's useful to have at least 1 of each faction just for when you get the daily quest to beat a faction crypt stage with a rare champ.

So, longer answer: certain oens are worth keeping, most aren't.

thank you all