I would think Yoda. He is very awesome and green, but he did master many ways of the force, and even found the way of immortality. He may not have been able to destroy the Sith, but he still taught Jedi for 900 years and embarked on thousands of missions and still posed as a thorn to the Empire's side.
you very much
If a tree would fall in the woods.....would the other trees laugh at it?