Building a community what would you use Substack or Medium

I am thinking about starting a "place" that provides well-written content about team enablement. I have been looking at the platforms out there. A few that come to mind are SubStack, Medium, blogs, ConvertKit. What would be a good platform and why would you pick it. Here are my main considerations - Its looks great (Yes design matters) - Content is discoverable by google (you know so people know it exists) - Easily shareable (at least a few posts will be worth sharing) - Cumulative growth. ( So I dont have to "send" emails every time to a list) - Some kind of network effect (so the platform does some work for me in bringing people)