The best genre or franchise films all tend to have one thing in common.. They are at heart just good films with a clear story (not always to taste but generally not a mess). Batman Begins/The Dark Knight/Iron Man/Captain America: The Winter Soldier/Casino Royale etc etc
This can even be seen in films such as Robocop (orginal) and its inferior remake.
Tell the story properly and the rest takes care of itself… once you move away from telling the story into fan service, or the studio starts to interfere (as was obvious in BvS and Age of Ultron) things start to fall apart rapidly.