As time goes on and people are remembering players from 50 years ago Ovechkin's name will still be up there with the all-time goal scoring leaders and his 9 Rocket Richards. He will likely be #1 in both categories for a long long time. While Crosby will be remembered I think he'll get lost in the shuffle of great centers like Messier, Yzerman, Mikita, Sakic, Beliveau, etc.
Personally I think Crosby is the better player, but that's not the question being asked. Hockey historians in 50 years will probably agree with me that Crosby is better, but that's a small percentage of hockey fans, most fans today know very little about the 60s hockey players.
Another factor Crosby fanboys won't like is this. Crosby is not particularly beloved or memorable, even here in Toronto. He's got a boring personality and his style of play isn't flashy. I don't blame him for shying away from the spotlight, I'd do the same. But the NHL is an entertainment business and Ovechkin is more entertaining.