Alchemy is the best combined with Herbalism. The new BfA Alchemy skill is named differently for the two factions, but the name is the only difference between them.Kul Tiran Alchemy is the Alliance version and Zandalari Alchemy is the Horde version.
Most BfA Alchemy recipes have 3 ranks. Rank 2 reduces the materials required to create a recipe, and Rank 3 have a chance to create multiple potions/flask etc. Higher rank recipes also give skill points much longer, so it will be a lot cheaper to level Alchemy if you first get Revered with the new BfA factions because you can use cheaper recipes for longer.