When comparing viva vs Solarized Dark, the Slant community recommends Solarized Dark for most people. In the question“What are the best Gnome Shell themes?” Solarized Dark is ranked 9th while viva is ranked 12th. The most important reason people chose Solarized Dark is:
There are ready-made packages for Vim, IntelliJ, Emacs, iTerm, etc. If your app isn't supported the website explains clearly what colors are used, so it should be easy to wrap up your own.
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 There are versions for a lot of applications or it's easy to make your own
There are ready-made packages for Vim, IntelliJ, Emacs, iTerm, etc. If your app isn't supported the website explains clearly what colors are used, so it should be easy to wrap up your own.
Pro It seems that is has been given the most thought
Judging from the description that has been given by the author, it seems that this color scheme has been designed with huge background knowledge about colors and relations between them.
Pro Works well with multiple fonts
Since Solarized has pretty good color separation it's easier to distinguish both thin and bold fonts.
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 Too much blue
People caring about the color intensity in their screens, will notice that this theme is not useful for night use. If you use software like Flux to dim the blues in your screen this theme loses its enchant.
Con Low contrast
Comments for example, have very low contrast against the background which makes it harder to read.
Con Vanilla version doesn't work with htop
Half of the usernames in htop have the same color as the background.
One has to use a patched version of htop.