Mining process, Metallurgy and Mastering the elements are my choices.
I am only mining to make money on AH, not for self crafting or anything.
What’s the best route to go?
Go with the one that lets you mine while mounted. Time saver when farming.
I am not sure what you are referring to? That is one of the 3 specific Specializations and will make me the most money?
This is a good guide about the specializations. What will make the most depends a bit on the market, but having more ore is generally a good place to start.