Just the big wins below. Of course there are other ways of looking at it, but...wins are wins.
MVdP
3x Ronde (24, 22, 20)
3x PR (25, 24, 23)
2x MSR (25, 23)
1x World Champion (23)
Add 2x Saxo, 2x Dwars, Amstel in stunning fashion, Strade...
Vingo
2x Tour de France (23, 22)
1x Vuelta (25)
Add 1x Dauphine, 1x Tirenno, 1x Basque
Would anyone deny that MVdP is a "Legend" of the sport at this point? Or at least that he will be when all said and done? I have him as a legend, whatever that means in my brain. Would I call Vingegaard a legend? I wouldn't. 3 Tours, probably. All 3 GT's, probably, but not unequivocally. So likely both are legends when all is said and done. But for me, MVdP has the more impressive domination of his domain at this point.
I really like MVdP and I really like classics. I don't dislike Vingegaard, but his personality and riding style do little for me. So I have bias. But I also would say that MVdP has an objectively more attacking style, a more committed style, and has wins which made me stand up and shout out loud watching, while Vingo...not so much. MVdP in my view has a better palmares in his discipline, and has a style and panache which make him a legend. Where Vingo is a great rider, but not terribly inspiring.