As of today Matthews gets my vote but Marner deserves to be in the conversation. He is kind of a "swiss army knife" type of player because like you say, he excels in all situations. He's starting to remind me (in terms of style) more and more of the great one. Both are perhaps known primarily for their passing skills, both have an excellent shot (that's something we can now say about Marner that wasn't true before), both are excellent skaters (though neither has blazing speed), both are a substantial threat to score shorthanded and both play in all situations. Gretzky lite is a helluva player!
You make valid points for Matthews and that's why he gets my vote but if someone were to cast their vote for Marner, it wouldn't be a big surprise because you could make a case for him as well.
I agree we shouldn't pit them against each other, I've always hated the player X vs player Y threads but I haven't really seen this happen up to this point with M&M and I think that's because until now, most people have seen Matthews as clearly the more valuable player. Marner is starting to make it interesting now though and I don't have a problem with someone saying so but yeah, I really hope it doesn't turn into a big debate cause I really hate those.