As a long time plex user, I'm tempted to try out Emby simply for one reason.- that is the GPU assisted transcoding. Plex still doesn't have hardware transcoder support.
TBH, I might have used something else entirely, but I had a Roku hooked to my TV which I've been completely happy with for the other channels it provides, and so Emby won out for me because it also has a Roku channel.