If I had to rate their popularity based on the fans' perceptions of their attractiveness, the ladies of Firefly would probably go Kaylee, River, Zoe, Inara. At least, that seems to be the reactions I've seen to the lovely ladies of Firefly.
You may be right about the aggregate reactions, but this Firefly
fan rates them in the following order: Inara, Kaylee, Zoe, River.
By the way, Morena Baccarin has now moved up into the #3 position for the year to date.