I have seen highlights of both Hughes and Kakko. My thoughts.
With Hughes, I see a game-changing highly skilled playmaker who skates around the ice as if it were a circus. So dynamic. Generates tons of chances for himself and his teammates. An all-around offensive machine.
With Kakko, I see a speedy winger, that plays well around the net. Has an average shot. Hustles on every play. Most of his scoring seems to come off opportunistic bounces.
I just see Hughes as a clearly (tier above) better all around player.