What are your must have Add-on's?

Hey folks..

I'm just starting my first forum and decided on XenForo.. so I'm so new I don't even know what to ask yet! but I thought I'd start with some basic configuration and core add-on's.. but being new I'm not sure exactly what those should be yet.. so if you could share some of the XenForo Add-on's you can't live without I know I'd learn a good deal..

Thanks Much