If you're a developer, OS X is great.
Windows is a second class citizen if you aren't using Visual Studio.
Linux is great - it's basically your deployment environment - but you often have to mess around with it a bit.
OS X is 90-95% of the benefit of Linux, but it just works™. If you want to get work done, that's a pretty good feature.
The trouble is that, if you want to run a desktop, there are basically no good options. Mac Mini is very limited, same with the iMac. The Mac Pro is not limited, but it supports such enormous expansion that the base config is extremely expensive, while not being very performant.