Im kind of conflicted, my go to answer would be The Walking Dead, but I have rewatched The Office probably 10-20 times, all the way up to when Steve Carrell left the show and couldnt make it more than a few episodes after that. The Robert California/Will Farrell, whatever, I dont even know. So that might be the one for me. I loved and still love that show, but Carrell carried it for sure. I did watch the finale and it was a great cameo for Carrell, but the show seemed like a former shell of itself.
The Walking Dead just kind of kept moving forward, at a glacial speed, doing the same thing over and over to the point where I eventually lost interest around the time that Glenn died. Seeing how they covered themselves in zombie guts to escape the hoard once or twice, and then immediately stopped doing that to survive was just lmao.