Hearthpwn

Should I buy Naxxramas or League Of Explorers and 2-3 packs?

People Say Naxxramas has more value, but LoE has more cards and is cheaper and I could buy 2-3 packs with the extra money.

Note: I have already done Blackrock Mountain 

LOE

Naxxramas

Check what your collection will benefit more from. You'll eventually unlock both anyways. Instead of buying 2-3 packs just save that gold to unlock wings. 

I don't know what cards are being released with each LoE wing, but make a comparison and see which which will benefit you. Wing 1 naxx or LoE? 

So IMO the essential Naxx cards are:

Sludge Belcher, Death's Bite, Loatheb, Haunted Creeper, Nerubian Egg, Mad Scientist, Zombie Chow and maybe Webspinner and Duplicate and Deathlord.

For the other cards and deck archetypes, you can generally get a substitution. Even though Kel'Thuzad is amazing in Ramp Druid, you can still substitute him. Druids can also use the new 3/4s or Mounted Raptor instead of Shade of Naxxramas, etc. If you don't really need any of the above cards in the foreseeable future, then I'd say go ahead and get LoE. Otherwise, Naxx would be the way to go.

As a side-note, I definitely agree with your assessment; Adventures do get you the best bang for your buck, and BRM isn't essential (Emperor Thaurissan use is dying down), unless you want to run a dragon deck.

Naxxramas for cards that are guaranteed to be usable. You're going to have to wait awhile for LoE cards to find their place in decks. 

naxxrams is ours :D 

It depends on  what deck you wanna build, as of now almost all decks need alot of cards from naxxramas.