I once had a guy that worked for me. After writing a conference paper but before turning it in for publication, he said "There is no one in the organization that is qualified to review my work." Strange thing is, no one in the organization would work
with him. He had burned all the bridges and left scorched earth in his path. I'm getting that same feeling here.
Boys, this was a simple question from the OP. If there was a single definitive answer, then there would be no debate. But we each define 'best' by our own standards; some may regard longevity and consistency as key factors, others may regard a five or eight or ten year peak as the key metric. Or still others may revere strikeouts as king, or wins, or WAR or ERA+ or whatever you want. But I will wager this - If you asked 25 major league managers and GMs who they would choose for their top left handed pitcher for their expansion team, there will definitely be more than one answer. That, is what is great about baseball - the thread that goes from Kershaw through Johnson through Koufax through Spahn and to Grove. We can have these discussions, debates even, and everyone gets their say.
Now, who is the 'best' looking actress in Hollywood? Remember, there is only one right answer.
