So the short answer is all of them. You may not benefit from them all equally right now, but having the option to make more things(should you choose) is never bad. You can make this a long term goal if you prefer, and level the non-interesting classes more passively. That would mean GC turn ins(when you have extra time or the daily item is easy/cheap), and using some spare beast tribe quests.

However, if you really want to focus just on CUL then these are my notes/what i would work towards.
ALC: 15+50 - Their CC skills are about generating more CP, which everyone wants.
ARM: 50 - This skill greatly helps with high difficulty crafts.
BSM: 50 - This skill is very useful for starred recipes(or anything above your current level).
CRP: 50 - This skill makes finishing HQ crafts much easier.
GSM: 50, 37+54? - The level 50 skill is another useful one for HQ crafting, their 37+54 skills combo to create a very powerful but time consuming method for completing difficult recipes.
LTW: Can skip - Their CC abilities get replaced by post-60 skills you will soon learn.
WVR: Skip/50 - You get an ability that almost completely replaces the WVR level 50 CC(which itself replaces their lower one), but the WVR ability is 0 CP and the level 62 one isnt so the CC might still have some limited use.