I don't know about Kuch being definitely ahead of Kane. Kuch had much better line around him then Kane. Can Kuch play on a line with Toews and a rotating cast member on the LW, mostly Caggs, and put up those numbers? I think that's a big question mark. Put another way, Kane created much of Toews's resurgence last year (1st time they played together in years) much moreso then Toews helped Kane. McDavid is hands down the #1, but after that, one can make a case for Kane. Needless to say, he's easily in the top 5 forwards and top 3 wingers in the game, anyone that would argue that doesn't understand the roles of a winger versus center. He's also easily one of the most dynamic players in the game. The analysts agreed why anyone could easily have awarded the Hart trophy to Kane...simply because he didn't play with Point or Stamkos.
Regarding Crosby, I don't disagree that his game can not be valued purely on points nor should it. Bergeon also. However for wingers, its much easier to value their play on goals and points. Therein lies the debate. I then look at who changes the game single handidly the most for their respective teams which is why McDavid is #1 without question. Kane single handidly won a lot of games for the Hawks especially last year...very few players can alone change the outcome of a game for a team. There are really no stats other then an eye test to see that and anyone who watched Kane last year wouldn't argue for a minute they did that.
For that reason, Kane has more value then Kapo which is why the inclusion of Krieder as a rental is a balanced trade. Now whether that is a fit for the NYR is open for debate IMO but also IMO anyone who would think Kaapo has more value 1:1 for then Kane is a silly argument given Kane's performance last year and Kaapo being an unknown entity.
A lot (okay a dozen or two, but still a fair number) of players can win a game. I suspect you mostly watch Hawks games. When Kessel was on the Leafs there would be a good 5-10 games per year he won for the team. He was never ahead of maybe top 15.
Kane is just a tad one dimensional IMHO to be quite at the top. While wingers aren't expected to be as defensively responsible it doesn't change the fact that someone being defensively reaponsible adds value.
In the end he is probably top 4 in offensive potential in the league with Kuch and McDavid and McKinnon and I suspect Crosby if he focussed more on offense (but he may be past that point in his career). But the fact that he isn't near the top 30 for defensive or play without the puck just pulls him down a little.
Either way he's a franchise player.
I do wonder how much longer he'll be in that top 5, and when Matthews, Laine (I believe last year was a blip), maybe Eichel, Hughes, Peterson (and who knows, maybe Kappo) knock him off.
It'll happen eventually, impossible to know when in advance