I like
Éliane and much prefer it to
Eliana, but that could be due to familiarity.
Eliana sounds like a rather princessy little girl, and
Éliane sounds like a calm, intelligent adult - but the Élianes I have known are all older ladies, & the
Éliane in my family is over 70.
Not sure where you are, but it might be tricky to use in an English-speaking country: it's quite likely to be confused with
Elaine.