One word...
Chromebook. Sleek, fast and efficient. Lets you live online, the browser is your computer. I love it. Windows is now just something I use at work, like a pen or a chair.
All the development tools I need I can find online and run either client-side in the browser or the cloud.
The machine itself, a modest Samsung, is small and light and has in just a few weeks become the computer I've most enjoyed using.