Ghost(Pro) is the hosting service provided by Ghost itself. It is the most "visible" host, as it is available from ghost.org. Also offering Enterprise plans, Ghost(Pro)—like the name suggests—is a powerful host best suited for medium to large sites.
The good
Run by the core Ghost team.
Automated Ghost updates.
Fully managed hosting.
Worldwide CDN.
The bad
Expensive entry point for smaller blogs.
Limits on page views, members and staff users.
Pricing
$36/month for 100k views, 2 Staff users, 1k members
$99/month for 500k views, 5 Staff users, 5k members
$249/month for 1m views, 15 Staff users, 15k members
14 day trial. Cheaper pricing is available with annual payments. Enterprise plans are also offered.