Well, what makes an anime or manga truly awesome, what makes it extraordinary, e.g. like Tengen Toppa Gurren Lagann or Higurasho no naku koro ni (kai) is the feeling, the heart and soul that have been taken into it.
This is not easy to explain, because, it's about the right feeling, let's put it this way: If you have a strong message in you, right form your heart, from your soul, you want to tell the world and you put all your heart and love into creating the best possible piece of art to convey your message, then the result will surely surpass most other works.