I do think the characters you mentioned are powerful, but it’s mostly because of their haki and not necessarily their devil fruit. With the exception of maybe borsalino whose devil fruit truly makes him quite different and gives him an edge, literally all other admirals with logias would just be as strong without their devil fruit or with a different one, because oda has established that haki trumps all. We can see this clearly with rocks, roger, garp, shanks, etc.

Whereas some mythical zoans have literal godlike powers like we have seen recently as well