re: the first part, let's say Panarin / Gaudreau / Marner then. I personally wouldn't put Kucherov in that MacK / McD / Drai / possibly even Matthews pantheon but I could see why some would. Wingers will naturally face a higher burden of proof to be considered the best but if there currently is a winger who can make that claim it would be Kuch.
Sadly I strongly disagree on the second part.
I can't point to only one team that has won the cup in the last 10 years with one or fewer superstar. Florida (Barkov, Tkachuk, Reinhart), Vegas (tbh probably wouldn't call anybody on that year's team a true superstar), Avs (MacK, Rantanen, Makar), TBL (Kucherov, Stamkos, Point, Hedman, Vas), WSH (Ovy, Backstrom, Carlson), Pit (Crosby, Malkin, Guentzel, Letang). All of those forwards are probably better than Bratt, almost certainly better than Nico, and all those defenders are better than the Devils' defensemen, at least currently.
And then you look at the other 'best-in-the-league' candidates and see how many cups they've won: McDavid/Draisaitl (crazy that they're on the same team): 0; Marner/Matthews: 0; Panarin: 1 (when he was a youngster and not a main player on that Blackhawks squad); Kaprizov (still early): 0.