Post has been deleted
The name [name_f]Hester[/name_f] seems to be a good compromise 
I think if you have sisters it would be an interesting blend. I like both names for the reasons you state. I like the vintage and soft feel of [name_f]Heather[/name_f] its got this timeless pop to it. And [name_f]Hestia[/name_f] is cute and I love mythology names. You have a winner no matter what you chose.
I’d stick with [name_f]Hestia[/name_f].
I prefer [name_f]Hestia[/name_f]; it’s pretty, uncommon but inkeeping with popular names right now, and the meaning is lovely.
[name_f]Heather[/name_f] does feel a little dated to me, although in theory I like its sound and imagery.
I agree with the suggestion of [name_f]Hester[/name_f]! It does err on the clunky-vintage side too, but more vintage than [name_f]Heather[/name_f], and I think its inclusion as a character name in the His Dark Materials books lends it a sort of feisty, starry, ethereal vibe too.
Or Hesper, which I really love and comes with the gorgeous meaning of “evening star”.
I love [name_f]Hester[/name_f], so [name_f]Hestia[/name_f] is more appealing to me.
[name_f]Heather[/name_f] sounds really dated. I’d expect people in their forties and fifties to be called this.
[name_f]Hestia[/name_f]'s lovely! [name_u]Unique[/name_u] but not weird, cute sound, fun mythological connection. [name_f]Heather[/name_f] sounds too dated to me, at least as a first name. I could see it working as a middle name to a more trendy first name.
I love [name_f]Hestia[/name_f], for the same warm, comforting homely feel you mentioned. Plus it’s different without being too unusual, and easy to say and spell. One of my close friends is called [name_f]Heather[/name_f], so I wouldn’t use it and it’s not my style anyway, but it’s nice enough.
When I hear [name_f]Heather[/name_f] I think of the plant, and it very much carries a similar vine to me in terms of earthly and warm.
I think it’s actually just starting to edge out of “dated” territory, although not a vintage pick yet, and with the popularity of nature names in general right now I don’t think it would be put of place, even if it’s not a super common choice currently.
I really dig [name_f]Hestia[/name_f] too honestly. Maybe it’s a little harder to wear in some regards but not a bad choice at all.