Last spring i pieced together a box from old parts laying around the house, it's running Plex through a Linux based OS named OpenMediaVault.
The thing that really appealed to me about it at the time was transcoding is all done server side and it works brilliantly, i can have a 40gb sized BluRay quality movie on the server and enjoy it on my large flat screen, but i can also play the same file on my phone, even remotely if i wanted, i can even play the exact same movie on multiple devices at the same time which is pretty trick. The only time it lags is if i have poor internet when i'm out and about.
I pondered going with Kodi, my cousin has a very nice Kodi setup at his house and he let me mess around with it a bunch, it has it's pros n cons. My Brother in law had a Plex setup that i also messed around with a few times at his house, i just ultimately decided i liked the Plex setup a bit better for my wants and needs.
One of my Brothers, my Brother in law, and one of my buddies all have Plex and share our Libraries with eachother, none of them run it via OpenMediaVault like me but that doesn't matter, it's kinda funny it's like our own mini version of Netflix, cept we have tons of stuff Netflix doesn't have or won't have because its too new.