Ghost's editor is probably the best I've seen. However if you're looking for content types or fields outside of what they provide its a challenge to add them be

Ghost's editor is probably the best I've seen. However if you're looking for content types or fields outside of what they provide its a challenge to add them because the CMS is written in EmberJS. As a straight-up blog (and membership platform) it does its job very well but I'm not inclined to use it beyond that.