I voted for [name_f]Diana[/name_f], but I think middles that don’t end in -a might sound more balanced with [name_f]Barbara[/name_f]. Some ideas that may fit your style:
[name_f]Lilith[/name_f] and [name_f]Elena[/name_f] from your list - i think [name_f]Barbara[/name_f] could be cool, but it needs a very modern-chic sounding middle.
I think [name_f]Diana[/name_f], [name_f]Isabella[/name_f], [name_f]Elizabeth[/name_f] and [name_f]Cassandra[/name_f] are too common if you’re looking for a unique name. And [name_f]Lilith[/name_f] is too similar to [name_f]Elizabeth[/name_f]. I would like something short and simple like [name_u]Lee[/name_u] or [name_f]May[/name_f]
I really love mythology associated names, like [name_f]Helena[/name_f] or [name_f]Cassandra[/name_f]. I’m set on [name_f]Barbara[/name_f] for the first name but I want something a little more delicate to balance out the first name.
I think I will scratch out [name_f]Diana[/name_f], [name_f]Lilith[/name_f] and [name_f]Isabella[/name_f] from my list.