I love
Vivian /
Vivienne. I go back and forth on the spellings, I really like both. But
Vivienne just looks a bit nicer to me, even though I'm not a fan of alternate spellings in general (even though it's a legit one, it's not the most 'well known', I guess).
Viviana is too frilly for me. Sounds like the name of a heroine in a romance novel, lol. But
Vivian or
Vivienne, esp. with nn Vivi, is lovely, IMO.