Best at what? What is driving you to want to switch? I like Icinga a lot. I won't bother reviewing it; is is very well known. Professionally, my last two gigs

Best at what? What is driving you to want to switch? I like Icinga a lot. I won't bother reviewing it; is is very well known. Professionally, my last two gigs have used Zabbix. Zabbix, architecturally, is a nightmare. Uses an RDBMS for storing time-series data, so it wastes a ton of space on historic data while managing to be far slower than it needs to be when querying larger ranges. Uses an agent. Has a proxy-agent that, while handy, encourages all sorts of sketchy, error-prone monitoring topologies. With 3.0, the UI has crawled out of the awful range, and is now merely annoying. Takes the all-singing, all-dancing monolithic approach for the main app, including features for drawing maps on big-screens. For all that, it works well. Give it the hardware it wants, be sane in setting it up[1], ignore the goofy features (maps, inventory, screens - I guess someone must of requested those), and it is very solid and very powerful. [1] The template system, pseudo-language for triggers, naming convention for variables and method of creating custom monitors take some getting used to. Expect to take the time to actually read the docs, and most likely to throw out your templates the first time you model your systems.