Re: Dedicated boxes aside
I ran with OpenElec on a pi for 6 months or so but eventually became frustrated with the lack of power and sporadic plugin support. It handled the basics fine but struggled with some codecs and high resolutions.
Now I have Kodi running on an Intel NUC, which also has Steam and a few other useful bits. It came with Windows 8, which is meh but it's been no trouble getting any peripheral (rf remote, various keyboards and mice and game controllers) hooked up, which was a pain on the pi. It works so well that it's now become our primary gaming platform as well as media consumption device.
My advice - if you want to fuck about or have low requirements and not much cash then go for OpenElec. If you want a bit more umph, with the added bonus of making a (kind of) Steam box, go for a NUC or similar.
Biting the hand that feeds IT
