Hosted Wordpress does not give you much flexibility, typically. Medium seems to intentionally enforce a style consistent with other blogs on the service. Tumblr's editing tools can be annoying sometimes but in my experiences it has been the most customizable.
I think it's worth it to host yourself, but if that isn't an option and you want flexibility then I'd go with Tumblr.
There are several hosts that will let you host. I prefer Github Pages because of the simplicity of Jekyll and that it uses Git and plus you get free Github CDN and a nice github subdomain.
Otherwise self-hosted Wordpress or Anchor Cms is the best option.
