I love them both, but I slightly prefer
Sophia.
It's very popular right now. I know 3
Sophia's (ages 22, 20, and 16), and 2
Sophie's (24 and 15). I'm pretty sure I know more, but I can't think of them right now.
I definitely see
Sophie as a name on it's own, not as a nn for
Sophia. I'm sure
Sophia would get shortened to
Sophie sometimes because that happens in speech, but it's really its own name.
so-FEE-a
I prefer the "ph" spellings, but either one is fine.
No, too much "ia."