I prefer
Helena. I like
Elena, but it doesn't work as well if the person isn't of Spanish heritage, imo. Though I prefer
Elena on any child as opposed to
Alana,
Alayna, Elaina, etc.
I love
Helena, and I prefer the prn. that rhymes with
Elena (heh-LAY-nah). I don't mind the Helen-ah and heh-LEE-nah, pronunciations but they pale in comparison to the first one imo.