Which AWS service should I use to host a Ghost CMS blog? [closed]

If you're happy with Lightsail stick with that. EC2 is more flexible but MUCH more complex and it's also more expensive. I don't think any of the other AWS services would be worth your time, Beanstalk is fine but takes more knowledge and work and isn't really required for a simple blog unless it's super high volume. Start simple. Lightsale.