My favorite is Sonya, because it's the way my grandmother's name is spelled. I don't understand the comment about the "Y" being "trendy" when it's been an accepted spelling of the name for decades (at least since 1938, when my grandma was born). Sonja would be my second favorite, with Sonia in third. The only other person I know with the name besides my grandma actually spells it Sonjia, which I definitely don't care for.