I love
Helena, but only pronounced
HEL ehn uh. The he LAY na pronunciation sounds too much like the tired, trendy and twee
Alaina/
Alayna/
Elena to me.
Helene, if I'm not mistaken, would be more correctly pronounced Ay LEHN or he LEHN; no long 'a' sound.
As much as I am fond of
Helena and
Helene, I would avoid them for the same reason
Antigone mentions. Inconsistent pronunciations all over the map. I think
Helen is a beautiful name, though, and you wouldn't have the issues with pronunciation.