What do you think about this?

I want to write a story that includes clones, How do you think the clones should be?

A perfect copy? (Appearence,Powers,Memories and Personality)
A Copy? (Appearence and Personality)
A bad copy? (Appearence)

Or do you have any ideas for this?
Or can you give me tips on Comicbooks, filmes or Videogames that have a similar concept?