The way I see it:
* Marner is a better prospect than Strome.
* However, I think Strome will be able to translate better to NHL, evening things out between them as individual players.
* Then I look at how likely the impact of their position is. Strome is 100% a center, and projects as a #1. There is not a more impactful position in hockey. Marner is a 50/50 case between center and winger, and even though I believe both have that ability to become the all-situations, centerpiece kind of player, I think Strome has a better chance.
* Then I consider team need, and we don't have any other possible top center outside of Nylander, and there is a pretty good chance he'll be a winger at the NHL level. While so early in a rebuild with so many needs you shouldn't prioritize team needs, I still feel like it is a small factor to consider. We probably have a few years to strengthen that center depth, but that doesn't mean you shouldn't look at doing it now if there are good options available. With how close things are between Strome and Marner in my opinion, this is still something that could tip the scale.
That leads me to give Strome an edge over Marner.
One thing is for sure. Whomever we pick between Hanifin, Strome and Marner, I'll mourn not getting the other two.