the media cover trump so favorably in part because they, themselves, are also narcissists.
not to the comically textbook extent that trump is, of course.
but i think a lot of the top media personalities similarly have egos the size of houses and think first and foremost in terms of themselves.
this is why, when it became obvious that hillary was under the weather, their first reaction was "why didn't she tell us before now"? concern for hillary, or getting the actual story about her condition, was of lesser importance. the bigger story, and the one with "legs", is hillary's decision to "hide" her pneumonia, and her "ongoing penchant for secrecy".
in short, they're pissed about getting scooped by some amateur video. ok, fine, you can say, particularly with the benefit of hindsight, that it would have been smart strategy to have said somegthing like, as she left the event early, "i've got a bug that's going around and am going to my daughter's apartment to hydrate and rest for a short while." but that brief commentary is a throwaway story at best, not an ongoing theme.
but the media continues to talk about it because they're narcissists -- it's all about *them*, how hillary's "secrecy" affected *them*.
trump, meanwhile, has concealed and probably lied about his taxes; and he has concealed and almost surely lied about his health. this is of no great concern to the media *because they haven't been scooped by amateur video*. trump's lies and secrecy haven't done any damage to *the media*, so the media is not punishing him for behavior that would be disastrous in the oval office. they don't care because it's all about *them*.
in fact, trump is treated better because he's a more capable liar and secret-keeper. hillary isn't good at it, and the video proves it. an amateur found her out. they don't mind trump lying and keeping secrets from the media as long as he's good at keeping the lies and the secrets from everyone else, too.