You don't have to pick now-- and you probably shouldn't. Armorsmith/ weaponsmith is a decision you make when you're relatively high in levels, and you've got a sense of perspective as to what will help you and what you want.
What's available in your guild matters, too. If your guild already has a weaponsmith, for example, it might be better for everyone for you to pick armorsmith. So don't sweat it for the time being.