From the Open Beta page:
Seems that the server names are decided then! Which should we all go for? I'll put this up for something like 24 hours so those in the Open Beta can all quickly hop into that server and safeguard their name, I guess.As long as the World you choose in the commercial release is the same as the World you choose in the open beta test, you will be able to transfer your character name. If you choose a different World for the commercial release, your character name will not be transferrable. For details, please refer to the beta test site.
Going by a quick check elsewhere, the leading choices of the public are Cornelia, Mysidia, Lindblum and Besaid. The ones few are opting for are Kashuan, Gysahl, Istory and Trabia. Wutai and Figaro are inbetweeners.
FFXIV STATUS BETA!