Probably Matthews, but it should be close. Matthews is a better natural scorer, but Draisaitl has the best playmaker beside him to make up the small gap in scoring ability.
Last season Draisaitl had 0.07 more GPG.
Their sh% was M = 14.7%, D = 21.6%.
Season before Matthews had 0.23 more GPG
Their sh% was M = 18.2%, D = 12.9%.
Season before Matthews had 0.14 more GPG
Their sh% was M = 14.3%, D = 16.9%.
Since Matthews entered the league Matthews had 0.10 more GPG
Their sh% was M = 15.7%, D = 17.4%
So far this season Matthews is 0.20 GPG higher.
Their sh% was M = 20.7%, D = 18.2%.
Too small of a sample size to make a concrete conclusion.
I don't see how people argue that this is Draisaitl. The one season Draisaitl beat Matthews he had an insanely high sh%
I am also in the camp that the younger player has more room to grow.
This isn't taking anything away from Draisaitl, he is a great player, I just don't think he is a better goal scorer than Matthews.