[name_u]Love[/name_u] both names. A complete tie. Not sure if [name_f]Sybil[/name_f] is too out there and [name_f]Stella[/name_f] is out of date.
I think [name_f]Stella[/name_f] is prettier than [name_f]Sybil[/name_f], but it’s very popular now. I think [name_f]Sybil[/name_f] is cool and not too out there. I feel [name_f]Stella[/name_f] is timeless (or at least it is in my country), but it’s a dealbreaker in my opinion that it keeps climbing the popularity ranking
[name_f]Edit[/name_f]: Actually now that I think about it, even though I adore the name [name_f]Stella[/name_f] I’ve grown to really appreciate [name_f]Sybil[/name_f] in this short time. Now I think it’s a great name 
I really love [name_f]Sybil[/name_f]! I would love to hear more of it. I don’t think [name_f]Stella[/name_f] is out date, but it is becoming very popular in the U.S.
I like [name_f]Stella[/name_f] more, it’s a great name. I definitely wouldn’t describe it as out of date, it is very popular right now.
I prefer [name_f]Sybil[/name_f]. [name_f]Stella[/name_f] is a fine names but has this tendency to cycle between trendyband dated. [name_f]Sybil[/name_f] is consistent, familiar, but never over abundant. And I find [name_f]Sybil[/name_f] to be a name that wears well at any age, whether the person is 2 or 82.
I’m not sure if I was clear enough, but [name_f]Stella[/name_f] is not out of date
I think they’re both great. [name_f]Stella[/name_f] is much more popular where I live, so I hear it around now and again. If I was naming my own child, I’d probably use [name_f]Sybil[/name_f].
I’m not a big fan of [name_f]Stella[/name_f] and I can’t quite pinpoint why.
[name_f]Sybil[/name_f] I like, it’s old fashioned but ready for a come back. I know someone called [name_f]Sibyl[/name_f] and she gets called Sibs as a nickname.
[name_f]Stella[/name_f] gets my vote-so spunky!
I prefer [name_f]Stella[/name_f].
Ooh I absolutely love [name_f]Sybil[/name_f]! She’s such a wonderfully strong and feisty, yet underused choice with so much vintage charm! [name_f]Stella[/name_f]’s okay, but I think [name_f]Sybil[/name_f]’s a head turner.
I feel [name_f]Sybil[/name_f] is way more out of date than [name_f]Stella[/name_f].
I don’t love [name_f]Stella[/name_f], but these forums have definitely made me see some appeal about it.
I slightly prefer the more interesting [name_f]Sybil[/name_f], but agree with pps that it’s on the clunky side. Maybe you could compromise and use [name_f]Sybilla[/name_f] or [name_f]Sybella[/name_f]?
I love both names but I gotta go with [name_f]Sybil[/name_f] 
I find [name_f]Sybil[/name_f] a bit clunky too and there aren’t any nicknames I love. So I vote [name_f]Stella[/name_f], which has a lot of drama and spunk to me. I would say it’s popular, not out of date (in the US anyway). I’ve been liking [name_f]Estelle[/name_f] as a slightly more unusual option.
[name_f]Stella[/name_f] is pretty but there’s always been something missing from it for me. I think [name_f]Estelle[/name_f] fixes that in my opinion.
Out of [name_f]Stella[/name_f] and [name_f]Sybill[/name_f], I prefer [name_f]Sybill[/name_f], but out of [name_f]Sybill[/name_f] and [name_f]Estelle[/name_f], I prefer [name_f]Estelle[/name_f].
I prefer [name_f]Sybil[/name_f].
Awesome. Thanks for the feedback everyone. This is very helpful. Brothers are [name_m]Oscar[/name_m] and [name_u]Charlie[/name_u]. Middle name is going to be [name_u]Ruby[/name_u] for sure. [name_f]Stella[/name_f] roles nicely with the other names but it does kind of bug me that there are a couple jewelry brands with that name. Keep your thoughts coming!