For me if I had to pick a good contender it would be the UK version of The Office.
I know many tend to debate how Ricky Gervais really fell off and how he repugnantly acts like a whiny centrist edgelord but me personally IMO I actually don’t think he was ever funny not even a little.
His big break through television was just so painful to sit through it’s so charismatically boring the characters are completely generic at best (notably Tim) or straight up insufferably unlikable at worst (especially the protagonist David FUCKING Brent) and most importantly the humour is just embarrassing.
Always seemed like The Thick Of It but without the nuisance tongue in cheek and charming satire.
A big part of why many of the things in this thread haven’t aged well, is because a lot of what made these shows original and unique was copied to death following the fame of the original.
If you weren’t there for the original release of a piece of media, there’s a good chance you’re not necessarily seeing it in the context where the accolades make sense.
Seinfeld basically invented the 3 camera sitcom and a lot of the key tropes in the format. If you go back today having not watched it before, the vast majority of it just comes across as a boring sitcom, because every sitcom to follow took notes from the way they did Seinfeld.
It’s the same with the UK office, it basically invented the modern mockumentary format as well as the cringe comedy era that followed (and gave us things like peep show). If you look back now without that context, it just looks like a generic combination of both those things.
Just to mention it, this is literally named the Seinfeld is Unfunny effect on TVTropes
I believe “I Love Lucy” is credited with inventing or popularizing the three camera sitcom. Not to dampen’s "Seinfeld"s contributions or the point of your comment, but I just wanted to add that small correction.