It really depends on your plans and your play style. I can only say my own point of view, that may be disagreable for you because you could have different priorities, collection, spending habits, ...So, my suggestion is to craft cards, which you are missing in your current decks. If you have your decks, which you are currently playing, complete, then you can think about some nice and useful legendary card from Classic edition, because it is timeless for standard. And if you want to do that, you can even more increase its value, if it would be neutral card, that can be used in deck of any class. That is just my personal opinion?
Please help.
I didn't find the right solution from the Internet.