for desktop I'm using arch linux with DWM , arch because it's just a single version of package that is well integrated in system with all dependencies, because of AUR and high community support with the nicest possible wiki, and because it's easy, with initial effort at the begging it's easy to setup and understand how it's working.
For server side usually debian(for single service oriented stuff), if are strong recommendations then Ubuntu(usually for virtualization tolls like openstack ).
For server side usually debian(for single service oriented stuff), if are strong recommendations then Ubuntu(usually for virtualization tolls like openstack ).