Aksana or Oksana? Technically, the second one is correct in true Russian form, but any which one sounds just as pretty. One convincing factor for anyone in love with this one might be that the Aksana form is actually starting to gain traction as a boys' name in the US.
The Oksana form is also technically more popular than Aksana for a little girl, but it really does boil down to being a matter of preference. While some will prefer the "A" spelling, many others will immediately fall in love with the infinite "O" letter. Both names are interchangeable though because although many words and names are spelled with an "O" in Russian, they are actually pronounced with an "A".
In either case, the name means "Praise be to God", but don't let that deter you if you're not religious. See it instead as putting all the favors in your daughter's corner. Some might even choose to spell it Oxana instead, but that's veering away from traditional Russian spellings.