If Mace Windu fought Sith and dark jedi and regular jedi like Malak, I would say he would be better. Mace certainly had the potential to be among the best duellists ever, I believe. But he was cut down, and being in a peaceful era it is doubtful he would have ever become the best.
Also, I would argue that had Mace NOT lived in a peaceful time, Vaapad would not exist. Why? Mace would perhaps succumb to the dark side because of the war... Remember, the action on his homeworld nearly broke him... Imagine Mace as a frontline general in the Mandalorian or Jedi civil Wars. He would be more jaded than ever, possibly removed and evil... And if that were the case, Vaapad would not exist.
Well, Qui-Gon's death was sort of cheap too, but no one ever really goes on about that. A jedi master defeated by getting jabbed in the jaw and then stabbed? Weak. And Obi-Wan's final strike may seem horribly cheap, but Maul pushed him into a well. Meaning? The Zabrak didn't have the advantage. I've watched that part so many times it's ridiculous... And Obi-Wan is clearly pressing the Sith.