I've been running my little media center / server on Ubuntu LTS for awhile now. It's been ok mostly but the occasional hiccup. I don't have any decent uptimes to report although this may be because I'm constantly tinkering and screwing around with it.

I've recently found that Debian with either backports or on Stretch can run the version of Kodi that I need to have a shared database across all devices in house. I'm torn between the two.

I was doing pros and cons

Ubuntu pro is I know it, and have used it for quite some time. I like LXD and find it much easier to use than basic LXC. Con is that I'm using 3 external repos (ppas) and I would prefer to have my system as close to core repos as possible.

Debian pro is fantastic uptimes and rock solid stability. As it is Ubuntu's father then I already know the system. I also would only need 1 external repo and have to compile a single program myself. Seems better than relying on 3 separate repos entirely.

The only con is that I would have to run my mythtv-backend inside a lxc container. Not a huge problem just a layer of complexity that I don't have to deal with on Ubuntu as it is in the main repos. I will already be running a couple lxc containers for minecraft servers so it's no big deal to add another one.

TLDR... Can't decide which to use for htpc / media server. Ubuntu LTS or Debian. I know it's a viewpoint question. Looking for viewpoints and perspective I may be missing. Suggestions on what would be the best course of action would be most appreicated.

Xubuntu is an elegant and easy to use operating system. Xubuntu comes with Xfce, which is a stable, light and configurable desktop environment.
Xubuntu is perfect for those who want the most out of their desktops with enough features for efficient, daily usage. I think MythTV recommends this distro..

I run the mythtv backend on its own, no mythbuntu or any other DE. i run it on my htpc which is headless, at least as far as keyboard and mouse goes. the server direct boots to kodi and i watch tv through that.

It's an htpc without a keyboard or mouse, so no need for a mouse based distro. it is used for nothing other than media, tv, and behind the scenes it does a bunch of stuff like minecraft servers, dhcp, dns among other things.

For all purposes consider this a server choice question, not a desktop distro question.