The original question:
Which one is correct?
Both are correct. If the question is "Which is used?" it is "It's me" overwhelmingly.
I agree with you.
This depends on how much you want your sentence to sound like
real spoken English.
For real spoken English, It is me...
For grammatically correct unnatural-sounding grammar-book English, it is I....
that by the way sounds a bit archaic...
I find it interesting that
Dr. Grammar writes:
"It is I or it is me? According to the
Merriam Webster's Dictionary of the English Language,"...instead of the old choice between right and wrong we are now choosing a style; it is a choice that is much closer to the reality of usage than the old one was...Clearly, both the
it is I and
it's me patterns are in reputable use and have been for a considerable time.
It is I tends to be used in more formal or more stuffy situations;
it's me predominates in real and fictional speech and in a more relaxed writing style."
It reminds me of "how are you? I am good" instead of "fine". Every one has been using (
predominantly ) " I am good" which became commonly accepted. I encounter simliar language situation in my native language too.
I mean, this is one of those odd instances where the gramatically incorrect form is so commonplace that it's now considered correct.
What do you think?