Karlsson
I'm a 64 yr. old man who was born and raised in Montreal. Being the contrarian that I am, I naturally became a Red Wings fan at the age of 5 because of Gordie Howe, who will always be my #1 idol. That being said in my, hopefully, humble opinion, Bobby Orr is the greatest, most complete player to ever play the game.
One could easily make the argument that we really never got to see Bobby Orr at his best as he suffered multiple knee injuries before and during his NHL career that required close to a dozen medical procedures. His career was effectively over at the age of 27.
I have no doubt that Orr would be as fast(if not faster) as McDavid in any head to head race. I know the tapes of his play really don't do justice to his ability, but I have seen Orr take the puck from behind his own net, lead the rush down the ice and be the first one back if the rush didn't result in a goal. Nobody could touch his speed.
Karlsson's offensive chops as a dman are easily are top 10. However he is nowhere close to either Orr, Lidstrom, Potvin, Robinson, Bourque or a dozen others in defensive ability