I haven’t played every COD by any means, but my understanding is that you stopped on a good note. Every recent COD I’ve tried feels like an absolute mess - mostly because of the aggressive cash shops that bog down the menus, and immersion-breaking skins/tracers etc. which I personally don’t enjoy seeing at all, like a gorilla and the clown from Saw. There are always bugs and crashes that literally never get fixed. Regardless of all that, they generally feel soulless and sloppy. There aren’t many FPS offerings these days, and Activision clearly knows they don’t need to be competitive. They just push a new one out the door every year, knowing fans love to hate the games and buy them religiously.
I did enjoy MW 2019 for a while, but MW2 did not hit the spot. Vanguard was extremely disappointing. Before those, my last COD was BO2. I’ve been on the fence lately about buying BO3 (2015) for a good zombies experience every time I see it on sale. But I know I would be playing solo because of the veteran stage those zombies players are in, and I have a feeling I’d get screeched at if I don’t know every meta strategy, so I end up passing on it every time.
Personally I’d say skip the Sledgehammer games and be skeptical and cautious about IW games, but give Treyarch’s next BO game a try if it doesn’t turn out to be an obvious bomb.
They’re almost all wildly successful and popular though, so there must be many fans who disagree - YMMV.