Recently I ran numerous tests on Flatpak and snap in an attempt to determine which would be more useful in my environment. After about a week of testing, I have arrived at a pretty 'surprising' set of findings. They are certainly not what I expected to uncover. If you are interested in reading the 'full monty' you may access it here:
http://eirenicon.org/2018/08/03/flatpak-vs-snap-snap-vs-flatpak/