Earlier quoted context omitted.
Medium sends out an e-mail with hand selected stories every week though and I find myself reading a couple quite often though. That's much less likely to happen with your own blog.
The real question you need to ask yourself though is, how likely are you to get your story in the email?
P(story read by audience|written in Medium) > P(story read by audience|written in self-hosted blog)
Medium will continue to be a better choice.