Pantheon.io
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I use Pantheon for all of my site building. It was originally built specifically for Drupal but you can now build Wordpress sites also. They give you three environments for each site: a dev, test, and live environment. Dev is where all of your development happens. Code is deployed through git or sftp, and you have a version log of each change. Test is where you test newly deployed code against the content that is currently on your site. You get these options:
Put in your log message and Pantheon merges your code from dev and your files and content from live. You visit the test site and make sure everything is bug free. Once you've done that you can move to the live environment and merge the code changes into live.
I have a couple sites hosted on there, but I mostly just develop. You can develop sites for free (limited to 2) and hosting starts at $25 a month. It's a little high for hosting, but it makes development much much easier.