I've used Plex since right after it came out. I tried Emby, but it was very similar. Similar enough that the fact that I was already heavily vested in Plex made converting not worth it at all.
Emby used to be the only one that truly integrated with Kodi, but Plex has the same integration now so that part is a tie.
IMHO if you've already got one, there isn't enough difference to put the effort into switching.
Live TV on Plex has been flawless for me.