I am based in China, so I use a paid VPN all the time. As of a few months ago, Netflix is blocking VPN's, so it is not possible to access Netflix that way. Almost all countries now have Netflix though, so if your content is available, you will still be able to watch.

I am not sure about HBO and VPN's.

Generally, the VPN's that are seen as the best are Astrill, ExpressVPN, Vypr etc.