I like
Juniper better because it has more personality.
June is sweet and that's about it. Next to
Esme,
June is a bit unsubstantial. Besides,
June is a splendid nick name, and if your daughter grows up to feel that
Juniper is "non-conformist" than she could always go ny
June or Junie or even Nipper/Nipsey or evn Uni if she wanted to.