we love the name Olivia too- however my mom suggested Lydia- which is close to Olivia but less popular.
I love the name Lydia!!!
If I had to vote between Nina and Olivia, I would probably go with Olivia. I've never been one to go for overly popular names though because I grew up with one and it really annoyed me. I graduated hs with 280ish people and there were 5 people who had my name!
Here's my issue with overly popular names - people feel the need to differentiate you from the others by adding something to your name and this can be as simple as a last initial OR it can be something that they feel describes you. I was always a very petite girl so I became "little _____" While I never minded being petite due to it being advantageous in the sports I played, it was annoying to gain that nickname even though it was always said with love by my friends and not meant to 'make fun' of me. The others with my same name also got their own little nicknames, some nice, some not so nice.