I think
Natasha is best.
Monica sounds weird, and I think it doesn't really sound that great for a little girl.
Natasha is a little common, but then again the popularity lists seem to think
Monica is.
I can see
Jordana,
Gabrielle, and
Natasha. All three names aren't short, but aren't extremely-over-the-top long.
Monica would stand out a little, I'm afraid.
I think
Monica Suzette flows better then
Monica Cecilia.
Monica Cecilia - both names are three sylables. That's why I think
Alessandra Elizabeth doesn't flow as well as
Alessandra Mae.
Monica Noelle would look nicer than
Monica Noel, in my opinion.