Hearthpwn

To clarify, I am currently sitting on 54 standard packs. With Alterac Valley Expansion right around the corner, I wanted to know if it would be more dust efficient to be opening my standard packs prior to the expansion packs or vice versa. 

I am trying to complete my collection from all sets. Currently I own every standard card card with majority of the wild cards, just dusting up the epics and Legendary cards that are missing. I have pre-purchased both bundles that blizzard offers for Alterac Valley and sitting on 145 packs of those, wasn't sure on which would be the go to route.

Thanks to any replies <3

p.s. I know I spend a lot of money on this game, I literally play no other games besides this because It's readily available on my phone when I feel like playing something when I am taking care of my infant son. I am spending my money on something I enjoy so save me the lecture about money management.