How can I replace the built in WordPress editor?

The wordpress editor is not an html editor, has never been, and it is literally not “marketed” as one since the 3.5 release.

You can put a lot of work and replace it, but an “off the shelf” html editor will not be a good replacement without lots and lots of modifications, as the editor has many integration points with wordpress and you will have to replicate all of them with your editor.