Yeah, I definitely don't agree with Boo's reply. If you were already endgame with plenty of epics and some legendaries, then okay, the number of rares that you should still keep would indeed be quite small. A lot of people have the practice of keeping at least 1 copy of each rare in case they are used in future fusions - but that's not absolutely necessary since you could still get the rares from the events/tournaments at that time, and anyway Plarium has made clear that they will only rarely use existing rares in fusions anymore.
But you're a long way from endgame obviously, having only 1 level 60 champ. There are still plenty of places where you may need some rares who are not super great, but offer some skill that you don't have yet on any epic or legendary. For instance, Coffin Smasher and Gravechill Killer are both strong candidates to use on your Clan Boss team right now, even if you will end up replacing them later. Athel is one of your best options for Fire Knight (and better than Elhain overall, really).
And now of course there is the Doom Tower, which adds additional skill requirements that can suddenly make people look towards champions they never had much use for before. For instance, any champion with Shield skills or Destroy Max HP skills is now a lot more important, like your Valerie.
As for the epics in your vault, I would add High Khatun, Ghrush and Zelotah (another Shield option) as champions you should be using.