If you aren't looking to make money, engineering probably still has the most impact. Other than that, blacksmithing is ridiculously cheap and u can make new gear obviously. Tailoring you can make bags for the rest of your life. Enchanting isn't great unless you don't have an enchanter already.
This expansion, it hasn't really mattered. I stuck with what I already had, enchanting, since it's easier to obtain mats which can get abit expensive unless you're rolling around in money. Also as the others have mentioned, it's pretty easy money when you start having excess crystals to sell off
I like Blacksmithing because it allows to craft you one or two pieces of gear that you might not have the luck to see drop or don't like the itemization of (I am looking at you BRF belts).
It will of course get replaced in mythic, but its a nice thing to have in the meantime.