When comparing viva vs XGnome Enhanced , the Slant community recommends XGnome Enhanced for most people. In the question“What are the best Gnome Shell themes?” XGnome Enhanced is ranked 5th while viva is ranked 12th. The most important reason people chose XGnome Enhanced is:
XGnome Enhanced supports Gnome Shell versions going all the way back to Gnome Shell 3.6.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Available in Blue and Orange themes
viva offers a blue and an orange them so users can pick how the theme looks.
Pro Supports many versions of Gnome Shell
XGnome Enhanced supports Gnome Shell versions going all the way back to Gnome Shell 3.6.
Pro Offers PPA for easy install on Ubuntu
There is an optional PPA for easy install on Ubuntu.
sudo add-apt-repository ppa:noobslab/themes && sudo apt-get update && sudo apt-get install xgnome-enhanced-gs
Pro Designed to be modern and minimal
The XGnome Enhanced theme is deigned to be modern and minimal. It is a very dark theme with clean lines.
Cons
Con Not finished
The them is not 100% finished yet, though the author does say he is working on it. Of course the latest commits can be seen on the github page with the last being from Sept. 2014.
Con PPA does not work
For example, you'd get errors like "Unable to locate package xgnome-enhanced-gs."