Vote for Android
The biggest advantage I can see in having an Android based UI - assuming it works this way - it that I do not need be be tied to the media sources that the TV manufacturer wants to give me and give long term support to.
Want ITV player - get it from the Playstore, want Plex again go to the store etc.
Need that latest version, no need to wait for a manufacturer supported version simply update it from the "standard" Playstore version.
If it really does work this way, then I for one, will be making my TV choice based on whether it has Android or not.
Note to the manufacture: locking me out of PlayStore and not letting me use Standard android media player apps will mean I will vote with my wallet!