I've pivoted during the last couple years to a lot of fiction. Substack is friendlier to a mix of stuff (Medium isn't very friendly to Fiction anyway). You can tell your readers how to filter out newsletters they don't want to receive by type. That alone is a huge advantage over Medium.

I don't have time to bury myself in building followings because I do a lot of side projects, sometimes outside of writing. Substack works better for that, too. I do what I can, and am (very) slowly building a base there.

The bottom line is that I prefer the Substack method of curation — readers. They vote with their subscriptions, paid and otherwise.