I dont want to set up my own domain to blog from, so my options are the free hosts, wordpress, blogger, medium, tumblr(?)
I want to blog on a platform which supports easy styling of code blocks, pretty text / html, and cross social site posting (to facebook, twitter etc.)
what are you guys using?
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.
I use Wordpress on my own domains as /blog It only takes a few minutes to configure. Get a few plugins & done.
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.