Interesting Danford over Robertson.
Personally, not how I would rank it, but often these things in this particular group ranking come down to value to the Leafs, rather than an individual talent evaluation. This is just my guess for next week.
Robertson everyone has seen for years now and expectation-fatigue has definitely set in, especially seeing two NHL coaches sort of stuffing him into purgatory every playoffs. He occupies an oversaturated niche in the roster/league: small, defensively suspect, offensively oriented but not overwhelmingly elite left winger.
Danford occupies a hard-to-get niche that the Leafs really want: two-way, physical, RD with size and snarl and mobility; imagine if the Leafs drafted Chris Tanev but he was super young and rather mean. His only real knock is he hasn't been proven in the NHL and how people evaluate defense using scoring stats.
Maccelli likely checks in over Robertson by virtue of having a successful season on his resume, and doesn't have the baggage of fanbase fatigue; he's basically the max age for this exercise so there's no real runway for personal growth, only better on-ice circumstances to ply his trade.
Cowan is the same niche as Robertson and Maccelli, but has a higher floor (PK, better skating, no tunnel vision) and as a play-chainer, probably a higher ceiling too; Maccelli probably has the lead on passing/vision at this time, but Cowan is still just a baby and has room to develop. Also more highly decorated in Junior accolades and there are way more eyeballs on him, hoping and coping for his success.
Knies continues the fine tradition (est 2016) of an Arizona-raised hockey player lording over the top of this list.