So you are ready to jump into the Zombicide: Black Plague universe, and are wondering what order to pick up the expansions, as even if you are not a completionist what is the order to rank them?
Zombicide: Black Plague core is the starting point, and there is a ton of playability in the box as-is. On a side note, there is no “replayability” in the game as even if you revisit each mission based on the characters in play and the different spawn and item cards it is a completely different game each time. PLUS there are a ton of printable new missions from the Z:BP community. One could power along on the core for a long time.
The only thing lacking in the core, which seems to be an annoying trend in board games recently is the dice. Given the game engine used multiple D6 dice, times multiple players you are going to want to pick up a few more D6s to have on hand.
Next step would be to add in Wulfsburg as you get a new zombie type (wolfz), some more heroes, two new tiles and a TON of new items, plus a new wolf-abomination. I consider Wulfsburg to be an auto-include as the additional item cards really give the game and complete that RPG feel of collecting and using magic items.
Building on this the next focus of your acquisitions should be additional characters- the Player Box 1, or the guest boxes. I recommend the guest boxes as they have some cool feats and abilities and the biggest factor in gameplay is playing with different party configurations.
Core + Wulfsburg + 2 guest character boxes is an amazing experience and a good place to stop if one is not a completionist.
Next addition are the NPC boxes, one to start as they give a few more vault items and offer a neat mini-game with them spawning and the heroes hunting them for rewards. It adds a nice twist without changing any complexity, tracking, or book-keeping in the game.
Follow-up with the Deadeye Walkers and/or Crowz expansion as they now change the mechanics of the game- movement and ranged attacks. To deal with them it helps to have more items at your control (Wulfsburg) and enough characters to build different parties (guest boxes).
Last would be the Abomination expansion as one already have two in play- one with the core and one more with Wulfs.
Finish up with the other NPC box and a few more guest boxes.