Jarno Saarinen ought to make it onto that list too. It's so sad that his career was cut very short.
I found this quote about him "Phil Read is not a man who has ever readily given second best to any other racer. Yet I once asked the best man he'd ever raced against. His options included Hailwood, Agostini, Redman, Ivy, Roberts, and just about anyone else you can think of in 20 years at the top of his sport - including, you suspected, himself. Read mulled it over for a whole nanosecond: 'Jarno Saarinen, no question', he replied. 'Different class'."