Many moons ago I read an article by a "white hunter" type who guided big game hunts. He was the "backup" to take out the game in case the prime hunter missed. He said the best was #1 buckshot--better than 00. I believe he was talking about jaguar hunts, but it was certainly one of the big cat breeds as the game.
If you search around there’s been a bunch of buckshot tests done that say #1 is the best overall. The gelatin tests are pretty convincing. Ufortunately loaded #1 is darn near impossible to find nowadays. #4 is out there and if you live in a neighborhood like mine it’s probably a good choice.