So which craft should you pick?
All of them. Yeah, that seems like a joke, but it’s not. If you have the patience, you should level up in all the crafts. This will give you more options to craft stuff to sell, and that gives you more flexibility. If the market for Superior Runes of the Ranger (Leatherworker) dries up, then you can go make Superior Runes of the Scholar on your tailor.
Being able to craft anything in the game you can sell, means you have more things to sell.
Having said that, if you’re going to pick just two, you need to pick two that can make the 4 primary ascended mats:
450 level Artificer, Weaponsmith, Huntsman, and Armorsmith can make a Lump of Mirthrillium.
450 level Artificer, Huntsman, and Armorsmith can make a Glob of Elder Spirit Residue.
450 level Huntsman, Leatherworker, and Tailor can make a Spool of Thick Elonian Cord.
450 level Leatherworker, Tailor, and Armorsmith can make a Spool of Silk Weaving Thread.
I’d recommend pick Tailor and Artificer. Tailors make light armor which is needed by the most popular classes in the game, which is one of the reasons damask is so expensive and profitable to make. Artificers make staves which are in demand by most of those professions. If you’re not crazy about Artificer, consider Weaponsmith, since they make daggers, which almost everyone needs two of.
The objective is to get your crafting at least up to level 450. Ascended mats are in high demand and the supply is very limited since they’re time gated – you can only make the thread, cord, lump or glob once a day. This makes them very profitable.
I’d recommended leveling all your crafts as high as they can go or at least to 450. However, I know crafting is boring for some, but if you want to make gold, you should level up at least two that can make ascended mats.