Marner has got to be one of the most overrated prospects in recent memory. He's the prototypical case of a high skill junior player putting up big numbers against terrible competition using skills that don't translate nearly as well playing against men at the highest level of hockey. He also happens to be an extremely high draft pick playing on a extremely good team on an extremely good line being watched by an extremely large fanbase. He's an impressive offensive talent, but is nowhere near close to the 3rd best prospect in hockey. Can thank HF's obsession over skill and Leafs Nation for that ranking.
Nylander is a different story. Kid has had ridiculous production at every level leading back to two years before his draft season. He's played and dominated against men at two different levels (SHL and AHL). While he possesses the skills often found in undersized skilled forwards - high level of hockey sense, silky-smooth hands, terrific playmaking ability and vision, he also possesses the skills that typically elude such players - a terrific shot and top-tier skating ability. Heck he's not even that small at 5'11, 190lbs. How Marner is rated over a player that is so clearly better than him by their own fanbase, is beyond me. If the Leafs have an elite talent in their system besides Matthews, it's Nylander. Hate to admit it but the kid is going to be a star.