I prefer
Callista. It's a beautiful, uncommon and memorable name. And you get the nicknames
Calla and
Callie. The reason I dislike
Estella is, a long time ago, I heard a really annoying chavvy song with the lyrics: "
Sheila goes out with her mate
Stella /It gets poured all over her fella /Cause she's says, man he ain't no better" etc. I remember song lyrics for ages. Now, I can't think of any name that contains
Stella without THAT running through my head.