Personally and I know this is a random in a string of posts already, but:
Server sides, so far I've toyed with: Twonky (most hardware DLNA out there now), lots of random transcoder/media server installs and pairings (win & Linux), and most recently Plex.
Clients: RasberryPi, Apple TV, Playstation 3 & 4, Xbox's, several low grade media fronts (samsung smarts, LG, etc etc), Boxee Box, Amazon Fire TV & Roku's.
Low maintenance that plays everything in both HD and full surround without need to be micro managing file types or encoding platforms and stays super responsive, the best pair I've found so far: Plex + Roku 3's (rarflix installed).
Can't beat it. Best platform for stability, speed and universal application (and trust me I've literally tried almost everything worth any salt).
I virtualize and test new stuff I find probably weekly, so if anyone has a different opinion throw it at me. :
-Colter