For background, my first CoD game was technically the original on my dad's PC back in the day, where I only played some of the campaign. Later when I had an Xbox 360 I rented CoD 2, 3, 4, and MW2 and played their campaigns some. But Black Ops was my first CoD online on Xbox Live.
When I think of CoD I think of Treyarch. The aesthetic of their games and the gameplay are the pinnacle of the series in my opinion. To me Black Ops 4 is no exception, and I feel people are looking at this game with a modern perspective, while Activision controls development the same way they have been for 10 years. I can't fault people for feeling underwhelmed after this many entries in the series and no positive change in the business model. From the perspective of the gaming industry, Activision is way behind and is Anti-Consumer. EA is often hated for their business practices but people often neglect to mention the ways they have changed their games to match the backlash. Remember codes that came with the game that were required to play online? Remember paid DLC/Season Passes in Battlefield? Remember pay-to-win microtransactions in Battlefront 2? The difference between EA and Activision is that Activision has done nothing in response to criticism, but somehow EA gets put over the flames way more. I think too much blame is put on developers when just like a government there are layers to the management of a project, and crappy, anti-consumer business decisions almost always fall on the publisher for video games.
Anyway, as for the three main developers, given what power they have, I think they all bring a unique flavor to Call of Duty. With the multitude of modes in Call of Duty from Campaign, Blackout, Zombies, Spec Ops, Extinction... it's kind of hard to compare all these games studios. Also one has to consider how many full Call of Duty games are under each developer's belt. Infinity Ward has 7, not including CoD4 Remastered. Treyarch has 7 if you include the spin off Big Red One. Sledgehammer has only 2, and showed up only recently. Is it fair to compare them all? Probably not.
For me Treyarch Zombies has been and will always be my favorite. Setting aside nostalgia, it perfectly blends cheesiness with realism to create a unique universe and aesthetic not present in many video game properties. To me, IW Zombies felt like it tried to hard to go for cheese, but it lacked any substance. WW2 Zombies felt like a bore to me, and I hated the tone. Exo-Zombies actually comes pretty close to this, and I think given more time to flesh out the story and improve the irritating gameplay, Exo-Zombies could have rivaled Treyarch. But alas, we are probably never seeing Oz again...
As I said, it feels unfair to compare zombies modes when Treyarch has had ten years to refine it and create good memories, while each other mode has only had one respective game. But speaking in terms of base gameplay mechanics, story, and aesthetics, Treyarch just takes the cake. Unlike a lot of people I liked the direction the Aether story went every step of the way, until about now... But I am giving Blundell the benefit of the doubt in saying I think he can end things in a satisfying way. The Storybook kind of depends on it.
But if I had to rank the other modes, it would go something like this:
1. Exo-Zombies - A solid mode that actually made me buy the season pass for this game. This was the first non-Treyarch zombies so I had to give it a shot. I actually had some fun in this mode, and I think the first three maps are actually good, but Descent is pretty awful to play. I think Sledgehammer did not get enough time to make the gameplay less annoying and tedious and to better flesh out the story, as this was a late addition, the first DLC being having the first map. I wish they could have stuck with this story and world, but I understand why they didn't.
2. Extinction - Not really zombies, but fits a similar niche. I would have told you I hate this mode until about a year ago, and I still kind of never ever want to play it. It is just far too stressful for my taste unlike Black Ops and Black Ops 2 which were probably the most slowed down versions of zombies. But after watching a lot of Jr Rizzo videos on Extinction, I've come to appreciate its design a lot more, and I think I'm just bad at it. It's a truly unique Co-Op mode, and I think without Activison's meddling, IW would have stuck with this is as their Co-Op mode.
3. IW Zombies - I had an initial honeymoon period with Zombies in Spaceland where I really enjoyed it. I followed all the marketing and bought Infinite Warfare just for this mode. I liked the idea behind the map, being set in the 80s, with goofy characters as opposed to the somewhat seriousness of Treyarch. I thought it would be a great complement to the series, but after playing it for a month or so I became so incredibly bored and frustrated with the map. It really did not stay on my radar long, and I was never able to pin down why. I was so disillusioned by it, I never bought the season pass. The game still sits on my shelf, maybe I could revisit someday?
4. WW2 Zombies - I really hate this mode, and I feel bad that I do. I can see there was a lot of passion put into it, and a lot of people around here and Jr Rizzo seem to love it. But it is just so boring to me. The gameplay is pretty solid, but nothing special. The characters don't feel special. The locations the maps are set in don't feel special. It feels like a knock-off of zombies, thru and thru, without the personality of any of the above modes. I wish I felt the same way about this mode as many others do, but I just don't. I never bought the DLC, only watching videos on them, hoping I would see something interesting but I never did. The grey, washed out look only added to my lack of interest. I disliked this mode, the campaign, and multiplayer so much, that WW2 is the only CoD I traded in at the store. I never do that with games, because I might want to go back someday. But I felt no connection with this game.
Am I biased? Yeah. But I'm willing to admit the faults in Treyarch Zombies as well, and there are plenty. I don't think the reason Youtubers and everyone else online only focuses on Treyarch is necessarily because they were the first to do Zombies. I mean, look at Treyarch and Infinity Ward. IW came first in the series and wowed everyone, but Treyarch put out some heavy hitters to change people's perception. I think none of these developers has gotten a chance to take a real, good crack at zombies. But I also think, ten years later, it may be too late. This style of game mode seems to be dying out when back then survival games were all the rage. The other modes may never be able to come out of Treyarch's shadow, and with Treyarch, they may all fade into obscurity given the way things are going.