Well it doesn't have anything to do with combat, but when you're running around in a sea of Human and Castanic females, you're going to be quite happy you picked that Aman female.
Castanic just because everybody here is saying Aman.
The racial are relatively useless except for Amani and Human and even then it's arguable. Amani's get gypped on basic attack distance and for slayer, Castanic male has the longest reaching basic melee attack (meaning you will cover more ground when attacking)
I recommend either picking what you like the look of most or try googling up "Tera attack comparisons"
I forgot to mention that Castanics also have nearly the same hit-boxes as Elin, making them slightly harder to hit.
The female Amani looks like a pink Cell from Dragonball Z
I am surprised so many people said Aman...Thanks for all the replies thus far! =)
I'm not... They're the coolest looking race. Who doesn't love dragon people?
Basically your choice for Female characters in Tera is:
1. Huge boobies
2. Loli Furry
3. Huge boobies
4. Bikini armor Succubus
...Or a badass Dragon girl.