First group kind of has better players overall, though mostly because they are old and proven.
However, this could not be more simpler, as there is only one possible answer:
Take McDavid with all his traits (agility, speed, hands, vision, passing, etc.), give him Laine's size and reach while retaining McDavid's speed and agility. And then give him the best shot arsenal there exists in todays hockey (or of all-time). That is Laine's shooting arsenal, of course. Matthews is kind of in-between player of McDavid & Laine already, and as such there are not many traits that would not be even better in either McDavid or Laine, but if you just would take Matthews forecheck and boardplay and therefore make that McDavid-Laine-Matthews -hybrid practically unbeatable.
I'm not sure what should be added from Barzal, since he is to some extent like lesser McDavid, but probably his in-your-face on-ice attitude. I don't know. His trademark puck carrying circles on o-zone would be pretty fun to watch, and even more if you add McDavid speed and Laine's size & shot to that equation.
That kind of hybrid would most certainly be the best player ever and also better than Crosby-Ovy-Malkin in most things. Crosby-hybrid remains to be best at protecting the puck and also with backhanders. And (young?)Ovie-hybrid remains to be a wrecking ball. And Malkin-hybrid is having superb hands and vision next to no-one. Still they would lose significantly on mobility, slightly on vision and handily on different shots and ability to score from a far.