[name_f]Do[/name_f] you pronounce [name_f]Sibylla[/name_f] and [name_f]Sybilla[/name_f] the same way? Which do you like better?
I say [name_f]Sibylla[/name_f] sih-BIH-lah (or sih-[name_m]BIL[/name_m]-lah, pretty much the same thing), which is how the Kingdom of [name_f]Heaven[/name_f] character pronounced her name. I say [name_f]Sybilla[/name_f] as SIH-buh-lah, or [name_f]Sybil[/name_f] with “lah” at the end, because it has [name_f]Sybil[/name_f] right in it. I prefer [name_f]Sibylla[/name_f] because of the character, personally. It gives off a more rough-hewn, tough-girl vibe to me. [name_f]Sybilla[/name_f] looks prettier on paper to me though. She’s proper and buttoned-up like a Victorian era noblewoman.
I pronounce them the same as you! 
I pronounce them the same way you do. However, I prefer [name_f]Sybilla[/name_f] to [name_f]Sibylla[/name_f]. Something about the -yl ending never looked correct to me. Either way, [name_f]Sybilla[/name_f]/[name_f]Sibylla[/name_f] is gorgeous.
I say [name_f]Sybilla[/name_f] and [name_f]Sibylla[/name_f] (I prefer this one, the y in the middle looks weird to me) both sih-bill-luh. I think. I’m really bad at phonetics.
I pronounce them the same way, emphasis on the -bill- part. I definitely prefer [name_f]Sybilla[/name_f]-- it just looks somehow neater and better. I like [name_f]Sybella[/name_f] best of all, though.
I have a good friend with a daughter [name_f]Sybella[/name_f]. … [name_f]Lovely[/name_f]! (Sigh- bella)
I say them sih-[name_m]BIL[/name_m]-a for [name_f]Sibylla[/name_f] and [name_f]Sybil[/name_f]-a or sigh-[name_m]BILL[/name_m]-a for [name_f]Sybilla[/name_f].
I say sih-[name_m]BILL[/name_m]-ah for both of them. [name_f]Sybilla[/name_f] is one of my favourites - so beautiful. I prefer this spelling for the nn [name_u]Billie[/name_u], mostly.
I also really like [name_f]Sibella[/name_f], and I’ve heard [name_f]Sabella[/name_f] recently but they feel a bit trendy for me.
I’d say them both like “sih-[name_m]BIL[/name_m]-a”, I think… but “SIH-bil-a” makes sense, too.
I [name_f]LOVE[/name_f] Sibil·la, which is like “see-[name_m]BEEL[/name_m]-la”, the L sounds make me melt.