It really depends.
I think right after humans, its going to be elves, then qunari, then dwarves. Elves are very popular in fantasy genres and most people love them (myself included), considering in the DA universe they are basically more attractive, magically inclined humans with long pointed ears, thinner frames. Plus, to those new to the DA franchise I can see elves as the second most gravitated to race due to fantasy familiarity.
Qunari come third because of two reasons. For those of us invested in the DA lore and universe, the qunari seem pretty limited in scope as far as the type of character portrayed. While humans, elves, and even dwarves are incredibly varied, we've only seen a limited viewpoint and 'personality type' of the qunari. However, they are horned giants, playing to that 'awesome factor'.
Dwarves come last because, really, few want to be the short fat guy/lady.
If I had a hierarchy based on popularity (not just BSN but people in general), I'd say this:
Races Alone:
Humans
Elves
Qunari
Dwarves
Race/Gender:
Human Male
Human Female
Elf Female
Qunari Male
Qunari Female
Elf Male
Dwarf Male
Dwarf Female
Race/Gender/Class:
Human Male Warrior
Human Female Mage
Elf Female Mage
Human Female Rogue
Elf Female Rogue
Human Female Warrior
Human Male Mage
Human Male Rogue
Elf Female Warrior
Qunari Male Warrior
Qunari Female Mage
Qunari Female Warrior
Qunari Female Rogue
Dwarf Male Warrior
Elf Male Mage
Qunari Male Mage
Qunari Male Rogue
Elf Male Rogue
Elf Male Warrior
Dwarf Female Rogue
Dwarf Male Rogue
Dwarf Female Warrior
^Keep in mind that's just a guestimate and NOT my personal views nor do I guarantee its entirely accurate.