AS A PROSPECT, I know it's a hard concept to understand but as a prospect (meaning before the guy is 25 and we know what he is like how we know what Toews is now), Matthews is a far better prospect than Toews was. Which is why Toews went 4th overall in an only okay draft year and Matthews went first overall in a fantastic draft year.
As for his closest comparable if he ends up living up to his potential I'd say Matthews is most similar in playing style as Malkin so far, imo.
Obviously, with knowing what Toews has become, if you gave me the option to trade Matthews for a 19 year old Toews right now I would do it, because potential is just potential. Matthews potential right now is most similar to Malkin / Tavares / Stamkos when they were drafted. He would however have been taken ahead of the aforementioned three if all of them were eligible in the same year as 18 year olds.
And if I get one response to this from someone saying "SO YOU MEAN MATTHEWS IS BETTER THAN TAVARES?! haha IDIOT" i'm going to never visit this site again. use your ****ing intelligence please, I know you have it somewhere, that's obviously not what i'm saying.