What do Du think about this?

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

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

oder do Du have any ideas for this?
oder can Du give me tips on Comicbooks, Filme oder Videogames that have a similar concept?