There is no debate in baseball. And given today's high bounce ball, much loosened foul ball rules, lower mound and so on he would've crushed his own statistics.
Barry Bonds' career has a stain because of PEDs, but I still consider him the greatest to ever play. Now we have Mike Trout, putting 9+ WAR seasons year after year. If he keeps this pace, he'll retire as the GOAT.
This will always be a subjective discussion, but for me, the only undebatable on the four major leagues is Wayne Gretzky on the NHL.
Also, check out my Top 10 players of all-time quizzes, I made one for each of the 30 teams.
Agree 100% with MBatistussi. You can argue every other sport except hockey. There's Gretzky, and then there's everyone else. Watching him vs the Soviets (1987 Canada Cup?) was jaw-dropping. He was already the best in the NHL by a mile. But that showed he was the best in the world. Nobody on the planet was on his level.