Thief crafting: difficulty choosing
Jeweler and Leatherworker are the most beneficial to you in regards to static stats. However cooking is incredibly valuable in that it can temporarily boost any stat you need at any time without sacrificing another stat.
For example, later in the game, exotics have a chance of dropping off enemy mobs. Those mobs are still pretty tough to kill. So with cooking, you can eat food that gives you more Magic Find to increase your chance to get good drops while still gearing for whatever stats benefit your build the most in PvE. Then, if you’re not concerned about increasing drop rates, eat food that temporarily increases a damage stat to kill things faster.
Personally, I’m a jeweler and a leatherworker and I’ve found that I have to stop and farm quite a bit to keep leatherworker current. With some changes they’ve made to the drop tables, the Fine Materials (blood, fangs, venom, etc..) that I need to make the gear drops fairly rarely so it’s making things a little tougher.
In hindsight, cooking would’ve probably been better because leveling gear can be bought with Karma or for fairly cheaply on the Trading Post and once at 400, the Magic Find boosting food can help you acquire mats for whatever third profession you may want to level.