Camille is much better, in my opinion. It makes me think of a really calm and nice environment. Fresh white sheets, white candles, the ocean, the sun.
Camilla reminds me of the wife of
Prince Charles and the whole messy situation with
Diana. I don't even read gossip magazines, but everyone still kind of knows their story. I remember someone once saying that apparently he once told her "I want to be your tampon" while cheating on
Diana. No, thanks. It's not a bad name and it is usable but I automatically think of her. Also, it is more likely to get misspelled.
Camila is actually more common than
Camilla and
Kamila is used in Poland and several other countries.
Kamilla is used too.
I prefer
Camila because it doesn't make me think of the whole royal gossip and because kah-MEE-la sounds nicer to me.