The often hated 6th Doctor is the greatest one... change my mind.
He's canonically the most brilliant of all the doctors. But there's an old saying:; "Genius is touched by madness." The way he dresses, the way he behaves,
even the way he speaks; everything about him shows that he has problems. Yet in spite of that he always strives to do the right thing.
He is a mentally ill hero;
and that's what makes him the best.