WP Engine! By far the best.
This statement comes from me, a guy who is into WordPress development since 2008. During my career I have used a lot of hosting providers like Hostgator, Siteground, Rackspace, BlueHost, DreamHost, JustHost etc.
So why do I think that WP Engine is the best?
Here are 3 features that blew me away:
1. Modern interface, which is not the classic Cpanel.
2. The backup system. Automatic backups are done every day. You can also do a manual backup with the click of a button.
3. This is the best feature: One click Staging (development) deployment and vice versa. With one click you can copy the whole site into a staging area which you can access with yourdomain. staging.wpengine.com . Then, with one other click you can copy your changes from the development area to the live site.
Other features include:
* CDN Integration
* A global Cache system so you don’t need to install cache plugins yourself.