Games and softwares: I store the installers, delete if I don't like it
Music: store them all, even if some songs in an album isn't my cup of tea
Videos: want to save all of them, but my storage is pretty small in the first place, so I pick the ones I really like
Ebooks: only downloaded a few, but still save them all
Mangas: usually save unless I don't really like it or no reason to reread