After years of building my own Mini-ITX's I gave up and started buying the teeny tiny Intel NUC's when they came out a few years ago. For a desktop (without playing games) they were powerful enough, fast enough with SSD, and most importantly quieter than any Mini-ITX I'd built (and, at the price of lack of upgradability, smaller).
I continued to -force- recommend them onto relatives who asked about a new computer, so when I built a new home media server the NUC was the obvious choice. And it's fine except the noise level seems to have gone up for some reason, which was one of the original attractions.
Then, I recently ran into the hibernate bug (mea culpa, I hadn't updated the BIOS in over a year), just as I needed to do some work, and instead had to spend an hour or two taking apart the box to get to the CMOS battery. Love diminishing.
So when I started to /dream/ about building a Steam machine, and saw that coming out in May is the Intel NUC Skull Canyon (http://www.intel.com/content/www/us/en/nuc/change-the-game-with-nuc.html), mixed feelings. The price will probably be the main decider.