alchemy is going to be good from the time you get it into the time you hit 300 skill.
leatherworking (the skill you were talking about) is good in the sense that you can make your own armor, make armor kits, some bags, and sell armor and armor kits for money, which you can use to buy potions and what not. however, being able to whip up a potion on the spot to help overcome whatever obstacle is in your way is a very valuable skill.
personally, i went leatherworking, since i like how it works in this game.
ive also heard engineering is good, because of the numerous contraptions you can use to increase damage and debuff the enemy (like nets for rooting people, and dynamite for mana-less AoE and more).
naturally, if you go alchemy, get herbalism as your second profession. if you go LW, get skinning. if you go engneering, get mining.