Gretzky is pretty clearly the greatest playmaker, biggest superstar, and maybe the best overall hockey player in history. That's pretty close to being beyond dispute, though some would say Howe and Orr have claim to being best-overall.
What is in dispute is Gretzky's claim to being the top goal scorer -- and that isn't really a new argument. Even during his prime, a lot of people felt Mike Bossy or Mario Lemieux was the better pure scorer. Across the course of a full career, both Howe and Jagr accumulated larger totals if we give them some margin for factors beyond their control (schedule length, leaguewide scoring rates).
Gretzky simply has the raw figure that nobody has beaten, 892. It's a bit like Joe Malone holding the single-game goal scoring record for over 100 years. It would take a freak event for anyone to ever score 7 goals in a game again, but it wasn't a freak event when it happened... Malone scored 7 only three weeks after Newsy Lalonde scored 6, and then Malone came back and scored 6 again only six weeks later, which was only three days after Cy Denneny scored 6. The raw record of 7 is somewhat meaningless as a result. 892 has a similar quality, being heavily reliant on playing during an era of 8-6 scoreboards.
There's no way Ovechkin will ever be the same level of star or overall player as Gretzky. But as rational-thinking people, we can look at the circumstances of his 724 against Gretzky's 892 -- what those numbers actually signify -- and make a reasonable conclusion that the 724 is actually the more impressive historical feat. And we can hope that Ovechkin hangs around to set the raw record, Marleau'ing it if necessary, so we don't have to have this conversation for generations to come.
