The information used below comes from the oldest sources we have: the Greek manuscripts of the New Testament. As you may know, the authors of the NT wrote in Koine Greek, which was the lingua franca of their day. The word numbers may vary slightly from source to source, but these are not going to change our final results.
So who are our Top Three writers?
The New Testament has a total of 138,020 Greek words in the Analytical Greek New Testament (AGNT).
Of those 138,020 words, the most prolific writers of the New Testament were:
AuthorBooks# of Words% of NT
Luke Gospel of Luke 37,933 27%