Of course everyone has their favorite girl in Anime, so making a list based on popularity would be very hard.
So I turned to who was the most searched for anime girls.
Starting in reverse order, we begin with......
10. Simca (Air Gear)
Simca, the leader of Genesis in the Manga and Anime "Air Gear".
Air Gear is a shōnen manga and anime by the mangaka Oh! great (Tenjho Tenge).
Both in the East and West, this Anime has gained a lot of popularity.
And Simca herself seems to have a fairly large fanbase.
She's popular enough to come in at number ten on the list.
In the Japanese Anime she's voiced by Rie Tanaka, and in the English dub, she's voiced by Monica Rial.
Simca also seems to be a very popular cosplay character.