Well theres different ways to go about choosing your country. If your gonna be a warrior Bastok is the best most people say, if your a monk San D'oria seems to be a nice choice. And if you are a mage of sorts Windurst is the best for you. Although that's not to say a black mage couldn't do good in Bastok or San D'oria.

Although you could go by your race for the ring you get for starting out in your home country. (Elves-San D'oria, Humes, Galkas- Bastok, Mithra, Tarutaru- Windurst.) The ring only adds a few stats to your guy, and becoems out dated the second you get 2 other rings. So it's not all that special.