They’re all great choices! To answer your questions:
I prefer the [name_f]Isabel[/name_f] spelling, to me it is a more chic and updated version of [name_f]Isabelle[/name_f]. I don’t think [name_f]Izzy[/name_f] is inevitable, plenty go by “Belle”. I definitely grew up with lots of Isabelles and it may end up being a bit of a “mum name” to the next generation.
[name_f]Emilia[/name_f] immediately jumps out to me as perfect with [name_m]Leo[/name_m]! Same international recognition and appeal. [name_m]You[/name_m] may get people mishearing it as “Amelia” at first but it is a small fix. [name_m]You[/name_m] can even use [name_f]Mia[/name_f] as a nickname for [name_f]Emilia[/name_f]. Or [name_f]Emmy[/name_f] or [name_f]Millie[/name_f] which are both so sweet with [name_m]Leo[/name_m].
[name_f]Mia[/name_f] does not feel stylistically different from [name_m]Leo[/name_m] to me at all. If anything, they may be a little too similar in their liquid vowel sound and 3-letter length.
If [name_f]Sophia[/name_f] is a long-time love and one you may regret not using then I would definitely keep it on the list. It was [name_f]Hazel[/name_f] for me, a name I have loved since I was 12 that I didn’t end up choosing because it rocketed to popularity when I was having my daughters. It retrospect, I don’t regret not using it, but I did have a year or 2 of pangs when I met other baby Hazels. My recommendation is if you don’t use your long-time love, make sure you are really sure about the name you choose instead, otherwise it could cause some grief. On that note, despite it’s long-time popularity and wide usage, I have not met one baby [name_f]Sophia[/name_f] in my 5 years of being a girl mum. Though like [name_f]Isabelle[/name_f], I do know quite a few my own age.
My vote is still:
- [name_f]Clara[/name_f] and now;
- [name_f]Emilia[/name_f] “Emmy” or “Millie”
Do take some time once she is here (if she is not already) to try the names out and see what fits before you announce it.