Do you know Murphy’s law? It says that Anything that can go wrong will go wrong. The last week wasn’t different when every website located on the same server stopped responding. That was a precisely planned DDOS attack, created by myself and pointed at me.
If you are looking for a comparison between the two plugins: Notification and Better Notifications for WordPress this is the article for you. The in-depth descriptions will help you see all the differences and will clarify which one is better in your case.