So when it comes to what you should do it depends in what you already have and what you want to get, be it as much dust as possible or some free cards.
Specific math: (Profit = crafting the card, when you don’t already have it)
Commons (Naturalize/Black Cat):
Profit per regular card: 5 dust
Profit per golden card: 50 dust
Cost to upgrade from regular to golden: 35 dust (360 dust saving)
Extra dust made by crafting a golden copy of a card you have a regular copy of: 10*
Rares (Doomguard/Devine Favour/Merkspark Eel):
Profit per regular card: 20 dust
Profit per golden card: 100 dust
Cost to upgrade from regular to golden: 80 dust (700 dust saving)
Extra dust made by crafting a golden copy of a card you have a regular copy of: 0
Epics (GloomStag/GlitterMoth):
Profit per regular card: 100 dust
Profit per golden card: 400 dust
Cost to upgrade from regular to golden: 300 dust (1200 dust saving)
Extra dust made by crafting a golden copy of a card you have a regular copy of: 0
Genn/Baku:
Profit per regular card: 400 dust
Profit per golden card: 1600 dust
Cost to upgrade from regular to golden: 1200 dust (1600 dust saving)
Extra dust made by crafting a golden copy of a card you have a regular copy of: 0
TL:DR - If all you care about is dust, by the time rotation happens in your collection you want Genn/Baku, 2 X GloomStag/GlitterMoth/Doomguard/Devine Favour/Merkspark Eel (any combination of 2 regular, 1 regular + 1 golden, 2 golden - makes no difference) and 2 X Golden Naturlize/Black Cat.
If you don’t have any of those 16 cards, then craft the golden copies.
So for example:
I currently own:
Genn/Baku
1 golden naturalize, 7 regular
6 Black Cat
8 Doomguard
5 Devine Favour
6 Merkspark Eel
1 Glitter Moth
0 Gloom Stag
I plan to craft 1 golden glitter moth and 2 golden gloom stag as they are essentially free. If I was going to DE all the cards after they leave standard. I would also craft 1 golden naturalize and 2 golden black cat for an extra 30 dust, but because I plan to keep them, I wont pay the 35 dust a card to upgrade.
So the total dust I’ll get will be: 3200 + 440 + 80 + 200 + 200 + 200 + 2000 + 3200 = 9520, having spend 4800 on the 3 golden epics (i.e. if I didn’t craft them I’d get 4720 dust, so I might as well get the free golden cards).
*commons have a unique property where the dust value for DE a golden is more that it costs to craft a regular, which is why you can make 10 extra dust per card.