I don't think this is an either/or situation. Medium's value is in exposing new, (arguably) high-quality content to its readers. Every so often, when you writ

I don't think this is an either/or situation. Medium's value is in exposing new, (arguably) high-quality content to its readers. Every so often, when you write an extra high-quality article, post it on medium as well, with a way for the reader to subscribe. It'll expose new readers to your writing and you still keep your content on your own platform.