The problem is not with the (\w{2,}?), because it will happily match to ab in

and

You are asking the regex to give you a sequence which is repeated, and you can either get the longest match (greedy) or the shortest one (ungreedy)

The only solution for your problem that I can think of, is to capture all matches that this regex finds (list context), then counting how often each captured sequence occurs, and selecting the one that occurs most often.