Oh, I just learned of this, and I am so saddened by it. Such a great driver, great competitor, and he always did it his own way. I remember clearly that 1976 Japanese GP. I always felt it took far more courage for him to stop in protest than it would have taken to drive on just for the championship. I don't know how Ron Howard and "Rush" treated that day, but I remember how it really was (according to the F1 media of that time).
It is a fools errand to rank drivers from different disciplines of racing, or from different eras within a discipline. So all I'll say about that is that Niki Lauda was clearly the greatest F1 driver of his era. And it was a very challenging era, fraught with dangers unimaginable today, and cars that were hard to drive fast, cars that demanded skill and rewarded those who had it. And Lauda always had it.
Godspeed Niki Lauda.