I love both, but I’m leaning [name_f]Sofia[/name_f] (maybe because it seems like people pick [name_f]Nadia[/name_f] just because it’s less popular? I don’t think the merit of a name drops as soon as it gets popular!). I have a coworker who has a [name_f]Sofia[/name_f], and I have a friend in the UK who has a [name_f]Sophia[/name_f], but I only know of both girls through their moms, and have never met them personally, so [name_f]Sofia[/name_f] still feels very fresh to me.
Plus, popularity isn’t what it once was. So [name_f]Sofia[/name_f] came in, last year, at number 14, with 9,650 little girls being given the name. If you divide that equally amongst the states (it wouldn’t be, since not all states are the same, but it gives you a number to work with), you get 193 Sofias being born last year in each state. I’ve done the math for specific states before, and it generally averages out to about 67 counties per state, so, again, this isn’t an accurate number, yada yada. So 193 divided by 67 is 2.8. That’s an average of less than 3 Sofias being born per county, to be divided equally amongst (in general) 20 or so school districts (and this discounts secular private schools, Catholic private schools, [name_m]Christian[/name_m]-but-not-Catholic private schools, charter schools, home schooled kids, etc.!). Which means the chances of her meeting another [name_f]Sofia[/name_f] in her grade, much less her school district, are fairly rare, although, obviously, it could happen! [name_f]Sophia[/name_f], which obviously ranks higher, and sounds just the same, tallies up to about 5 per county per year, which will probably mean that she might go to school with another [name_f]Sophia[/name_f], although it may not necessarily be in her school district. There may be three Sophias and two Sofias, at the absolute most, from Kindergarten through 12th grade, by this math. [name_m]Just[/name_m] some numbers to look at, because I think a lot of people come on here instantly hating popularity, but it’s not what it once was at all.
That being said, I’ve probably met less than a dozen Ashleys, realistically, and I grew up in its heyday. So popularity doesn’t bother me too much, and I like that my popular name made me feel like I sort of belonged, even though I felt like a bit of an outcast, growing up.
I do adore [name_f]Nadia[/name_f], and both meanings are beautiful–“wisdom” and “hope”–but [name_f]Sofia[/name_f] has a bit more of my heart than [name_f]Nadia[/name_f] does. It probably helps that it’s much easier for me to come up with a combo I love for [name_f]Sofia[/name_f], too. 
Good luck!
