Some Questions

[Anova]

Definitely level up both. Both classes benefit tremendously from leves, so you may have to spread it out. I would start on crafters first, simply because you can get all your mats from the local city vendors or from your fc vendor (if you have a fc house). Gatherers benefit a lot from chocobos and although you three are past that point, I would recommend newer players to wait until they get chocobos before attempting gathering.

Also, some other tips you might know:

If you are leveling a crafter, I would prioritize Carpenter, Goldsmith, Alchemist, Culinarian, and Goldsmith to level 15 (in any order). Access to the lv.15 cross-class abilities of those classes will allow you to guarantee HQ items. This will help you gear up your other crafters/gatherers as you immediately have the best possible gear and can spiritbind faster (helping you make that huge jump from level 50 to 51). Turning in HQ items also gives 300%xp for the actual craft and 200% bonus on the turn in. It will save you a ton of money if you are too lazy like me to hunt stuff like leather or monster drops and buy mats in bulk on the market.

Starting from level 30, you will see leves with half the xp reward and asking for multiple items. These leves allow up to 3 turn-ins on a single leve, providing a possible total of 3x the gil, reward, and xp. These are very useful if you're running low on leves or need more gil.

There is a huge spike in crafting difficulty starting from level 50 to 51. I would recommend saving and spending your craft/gather materia then to augment your gear. You could buy the Revenants Toll gear to make it easier too, but doing so also spends a lot of seals and rare gathering nodes on gear you will replace in 3 levels anyway. If you're not hurting for seals or have a lot of rare mats stored up though, but it's not the most efficient. You'd probably do better by selling the mats on the market though. A lot of those are used for airships and can be sold for a pretty penny. You can then fund mats for other mats you need at that level.

Also, look out for specific leves at lv.45 in Coinoch. The returns on some of those actually let you make more money than you spend and will essentially fund themselves so you don't have to farm mats (aside from a modest starter). They have not changed that to my knowledge, so it's a good spot to recover any money you've lost. We had 10 crafters exploiting those levequests to help pay for a mansion That's how much money can be gained from it.