Of non-bellyitchers

Since Diddy Mao is apparently at a stage of his blogging career where he will only respond to direct prompts, and since it’s been a while since we’ve gone ahead with a debate-oriented topic, I am going to ask him to answer a little baseball question for me. Any other theblog.net readers are welcome and encouraged to follow suit, and give me their answers to the query. Said query is this:

It is fairly well established that, despite this being the Age of the Juice in baseball, we are witnessing four unequivocal masters at work on the pitching mound, in Roger Clemens, Randy Johnson, Greg Maddux, and Pedro Martinez. So, I want Dids and anyone else to give me their opinions on the following two questions: Which of the four do you think had the best career, and, alternatively, which of the four, at the absolute zenith of their respective powers, was the best? In your answers, please give rationales, and for the second question, please tell me how you’re defining what a player’s "peak" actually is (like "1 year" or "3-year stretch" or whatever).

Let’s hear what you ‘mos have to say.