The title of this thread makes it look like Dana is the only answer lol.
Best female definitely Nadine Beiler. Her voice got her into the final.
Best male vocalist is Jedward.
Lol jk Amaury Vassili
Male Amaury Vassili (even though I don't like the song nor him)
Female Evelina Sašenko maybe? There are quite a few... Maja Keuc, Poli Genova, Nina... I don't know...