Ask HN: What IoT development boards are you using?

We are interested in writing a series of blog posts comparing how existing Fog Computing frameworks play with various IoT development boards. Naturally, we want to learn as much as we can and make it useful to the broader community. Thus we're wondering:

What devices are you using? What boards would you like to see evaluated? What type of applications are you writing? And what is the most time- or resource-consuming function within your applications?