as
Kiran, an East Indian name.
Of the combos you have listed, I like
Kieran Ava the best.
Ava matches girl-Kieran's edginess and almost-androgyny (I don't see
Ava as frilly-feimine at all, but rather an energetic, boyish name, no clue why). The other names make the fact that
Keiran is generally a boy's name glaringly obvious, and they look awkward together - like
Gregory Annabelle or
Howard Emily.
As for myself, I just wouldn't use it at all, it's not my style. Too plastic-pretty.