I like paperback for reading, such as novels or whatever book I’ll be holding for an extended period of time.
In contrast I prefer hardcover for books that are more visual in content or that are made to be consulted briefly such as encyclopaedias, dictionaries, etc. Or if I want it to stay open and flat on a surface, hardcover.
I’m ambivalent about small/medium sized gift books or trinket books. Those can be whatever type of cover.