Med, med, med. Focus = good stam regen, a little mana regen. Med = good mana regen. As an archer, you're not going to be hit very often, so you're not gonna have stamina problems. On the other hand, you'll be using lots of mana for bush/chiv spells. Mana regen is what you want.
Of course, you'll need to ensure that your suit is medable. ;-)