pronouns - "That was me" vs. "That was I"

When telling a story about myself from the past, I have found myself in an internal debate over whether the correct way to segue into the present is:

That was me twelve years ago.

Or:

That was I twelve years ago.

My instincts tell me the first is correct (object pronoun after a verb and it sounds better to my ears). But, I'm not sure if pronouns after linking verbs should be object pronouns. Which is correct?

Answer

Professor Geoffrey Pullum has this to say:

Myth: Expressions like "It was me" and "She was taller than him" are
incorrect; the correct forms are "It was I" and "She was taller than
he."

Pullum responds: The forms with nominative pronouns sound ridiculously
stuffy today. In present-day English, the copular verb takes
accusative pronoun complements and so does "than." My advice would be
this: If someone knocks at your door, and you say "Who's there?" and
what you hear in response is "It is I," don't let them in. It's no one
you want to know.

"People have been living in fear of grammar rules that don't exist,"
said Pullum, who wrote The Cambridge Grammar with Rodney Huddleston of

the University of Queensland, Australia. "We're going into the 21st
century carrying grammar books from the 20th century that haven't
shaken off grammar myths from the 19th century," said Pullum.