Still leaning slightly towards Marner, this is more of a Babcock thing though because he doesn't put Marner in the position that a lot of other stars are in around the league.
Rantanen has had a stellar season and no one can or should take that way from him, but their positions to succeed are way different IMHO.
Marner is one of the best PP players in the entire NHL, but Babcock controls his(and all players) PP time, Marner only gets 2:11 seconds of PP time a game per average. Rantanen is getting 3:44, that's pretty significant. Wouldn't surprise me if Marner's numbers took a big shot up if you gave him another minute and half on the PP.
There is no doubt though that Rantanen has had the better season, but they're two different players in two completely different situations and roles.
I wonder if we will ever see Matthews with Marner, but that's now how Babcock operates, he wants Marner driving his own line, which I totally get. He's carried every lines he's ever been on for the Leafs.