Torn here, they are all nice names! Always liked Caroline, and Vivian/Vivienne has grown on me over the past 10 years. Tbh I haven't met a Susan(nah) under 40 - more Suzannes, though still infrequent - whereas know quite a few Heathers, perhaps because I live in Scotland.
Not very helpful sorry but you can't lose with any of these imo.
They are all lovely names! Susannah Caroline is my top combination for a FN & MM and has been for a long time! They are both chosen for family reasons on my part, but they are both beautiful, classic but not overly common names. I have seen Susannah appearing a bit more, but have yet to meet a young child/new baby with this name recently.
Heather & Vivian are lovely as well, I would struggle to chose out of your list!
Since I have had to rule out Harper as a first name (not because of posh n becks but due to rhyming with my potential future surname)
Which of these girls names do you hate the least...
Vivian Caroline Heather Susannah
Am trying to find the middle ground between 'every other girl in the same school class' and 'so odd nobody has no idea how to spell it' without going down the 'old classics about to explode in popularity'