Mila is ok. I think it feels a little too cutesy/youthful though.
But I really love Nina, have liked it a lot for years. It's so sweet and fun and orange. I also pronounce it NEE-na. I guess an uneducated(?) pronunciation of it is Nine-a. My Grandma was born May 9th and said her mother always joked she should've named her Nina May. (Pronounced Nine-a). :)