Lol, not even close to the best in his prime. Pedro, Johnson, and Koufax all had 2 seasons better
than Maddux's best season by bWAR.
Maddux's best season by ERA+ was 271. Pedro's was 291 (!!!).
By WAR7 (only picking each pitcher's best 7 years), Clemens kills Maddux, and Johnson and Pedro both narrowly beat Maddux too.
Maddux was a great, great pitcher. But his best argument is longevity, not pretending his prime was the absolute best out of all these guys.