That's a really good question!
If this was posed 10 years ago, I would've said Brett. He played
hard every point, and though he had some power, was not among
the elite in any part of his game.
Today, I would say that it is Dania's Beitia. That he hangs (and
occasionally wins) the late games without having any particular
strength in his game is telling, considering the competition.
You could argue that about Olate, too.