I’ve been using Munin for myself to replace Cacti and been generally liking it. As someone who has used Cacti for a long time I never seem to get my head around it totally. Something would go wrong and it would never be easy for me to find out just what was failing as I thought it should be. But really what I liked was the ability to send me some email alerts. My monitoring needs are not grandiose so this was fine for me. Except the default email alerts aren’t the easiest to read, but they are short.