Must agree that Secretariat was the better pure racing animal. His times in winning each jewel of the Triple Crown are STILL the records, which is astonishing.
The horse I know as "Big Red" (I was born in the 60s) almost didn't get credit for the record for the Preakness - the morons at Pimlico (and I'm from Baltimore) screwed up the timer. Replays have shown that he ran in record time, but it wasn't until 2012 that it was officially recognized.
MOW set 7 records and equaled 1in the space of 1 season of 11 races. 3 world, 2 Anmerican and 2+1track. From 1mi (WR) to 1-5/8mi (WR). Often with big weight concessions. He never, ever spat out the bit.