I'm going to go with one vote per person per thread. Sorry...
Rats... Time to cut down the options!
Harpies are flying monstrosities of awesomeness, plus they have adorable babies (like chickens combined with regular babies for twice the adorableness). Certainly a worthy choice.
Merfolk, on the other hand, live on or near the sea, which is a certified advantage.
Fairies are fairies, but since we already have a fairy dynasty, I would probably let it drop.
Centaurs could also be nice, even if they require special buildings. Centaur no nayami proves that they can work even as a modern civilisation.
Finally, playing as a race of Gorgons could be awesome, and not just because of the whole lizard thing. Trying to diplomacy without turning whoever you talk to to stone could be a fun trial.
In the end, though, I have to say
[X] Harpy
Because now Harpy has enough votes to survive the culling.
Question: Of the three chosen races, could the remaining two perhaps become minorities in the civilisation (sorta like how Endless Legend does it)? Because that could be pretty interesting, to have multiple races living within the same civilisation from the get-go.