It was entertaining at first, but its taken a turn into really really sad territory to see folks spending literally thousands of hours and more than a decade focusing their attention and emotional energy just tearing down one single player with any kind of mental gymnastics possible and the same arguments for years. The bitterness required to do this is a bit unsettling, at best.
Anyway, as for the thread topic. McDavid is a hell of a player and is certainly above Crosby in terms of offensive point production, but it's hard to say there's any player in the league who is "a tier above" Side from a holistic point of view.
People who watch him a lot will, of course, tend to overrate him. People who don't watch him will tend to underrate him. And with most things in life, the truth is in the middle. Personally, I think it's probably closer to the side of the people who actually watch the games, but that's just me.