Martin Brodeur and Patrick Roy have both enjoyed two of the best careers in NHL history between the pipes. The general consensus is that when Roy retired he was the best goalie of all time. It was also generally agreed upon that by the end of Brodeur's career, he would most likely overtake most, if not all of Roy's and the NHL's career records and cement himself as the top netminder of all time.
The arguments for Roy are that he has one more Stanley Cup (4-3) and actually beat Brodeur head to head in a final in 2001, he has three more Conn Smythe awards (3-0) and that he didn't have Stevens, Neidermeyer or the trap defense in front of him to pad his win stats. I would dismiss that argument by saying that the list of scorers in front of Roy, which included the likes of Joe Sakic and Peter Forsberg, were far superior to the mediocre offenses Brodeur had as support.
I also don't think you can fault Brodeur for not winning the Conn Smythe. In his last Stanley Cup winning performance, Brodeur put up seven playoff shutouts including THREE in the finals which also included a shutout in game 7, only to see the award go unjustly to Jean-Sebastien Giguere.
That being said, the arguments for Brodeur are numerous and significant. I've narrowed them down to the top 5...