I am NOT an English teacher but it all depends on what phone you are answering and on the people who are calling you.
If you are answering your own phone when a friend is calling you, you can use any of the ideas you listed, except for "I am Mike." This would sound like you were introducing yourself to someone for the first time.
If you are answering a phone at work or in any situation where you need to be more formal and polite it would be better to either say your full name or to say "This is Mike (surname) speaking."
Student or Learner