We have chosen Sienna for this baby. I'm surprised tbh as I never considered it before but I like it very much now. I would rather use one N (Siena) on principal, but I prefer the look of the 2Ns 🤷♀️😂 Also it might be easier for people to spell it correctly if 2Ns is better known name-wise. Not a huge issue though.
While I love Sophia/Sofia I do agree that it is very common, although classic. So it really just depends if you care that it is well used or not!