Currently working as a Marketing Manager and Full Stack Web Developer for a group of small companies, I spend most of my time keeping up with best practices while using the typical category killers like Wordpress and Magento.
My workstation is a Macbook Pro Retina. I made the switch from Linux and Windows 7 last year and haven't looked back. It's far from perfect, but it's the best of both worlds in too many ways.
That said, if Adobe would port to Linux, or if Linux would get apps in those categories which could allow the same level of productivity with graphics and video, I'd have a hard time justifying using a Mac.
As it is I still use a lot of Linux virtual machines and web hosts.
I love Open Source. I strive to use FOSS projects wherever I can. I contribute to them whenever I think I'd be more help than hindrance.