Also Dutch here. Developers go with Windows if they do not get a choice; unfortunately, most major companies demand everyone uses Windows.

I'm fortunate to be working for a consultancy company that just gives everyone a budget to buy their computer. Most people have a Macbook, with the odd exception that simply has a hatred for Apple or can't get used to it.

I would argue that development tools are much better for OSX. It's like Linux, but usable. A lot of commandline tools just work out of the box under OSX, where you have to go through hoops, hope there's a port, or install a bash emulator under Windows.

Of course, .NET developers will be using Windows.