Phoebe is definitely my fave, the other two aren’t really my style, but I love Phoebe. It’s classic yet quirky, ages well and is just a nice name imo. If I had to choose from Ione and Iona, then I’d go with Iona, as I prefer the look and sound of it.
IonaIone looks like Lone lowercase and my phone recognizes it as a typo. At least Iona looks like Lona. Phoebe is okay but sounds like a name a big bossy girl might have.
I like either Ione or Iona. Kind of leaning towards Ione. Partly because the meaning (Violet flower) is so lovely. Eye-OH-nee (Ione) and Eye-OH-nah (Iona) are my pronunciations.