Television

Nah, you just have to pick the right shows. Gunsmoke, bonanza, and most of the other Westerns hold up very well. There are stylistic differences in the acting of course, and the writing makes different assumptions about what the audience has a default worldview, but if you want to compare eras, you can't use those criteria because it skews to heavily to the most recent eras.

If you take the story structure, directing, cinematography, and acting as the criteria, you can make comparisons that are viable.

The Fugitive holds up against any show from any era, as a non western example. Marcus Welby did pretty good as a medical drama, though St Elsewhere and ER top it by a lot.

And you can't dismiss the franchises. Mission: impossible and Star Trek. Both products of the sixties.

You've got cops and legal shows like Dragnet or Perry Mason that hold up okay, certainly no less well than some of the alternatives from later eras.

Oh! And The Prisoner! Perhaps the original mind fuck tv show.

You've got dark shadows, which doesn't hold up as well as it could, but it's still something that stands out and is enjoyable to new audiences.

You've got Dr Who as well, though I don't think it's fair to call it a sixties shows since it spans decades (and the sixties era is the weakest era imo).

And, you've got The Twilight Zone that also has spans in other eras, but the sixties was the best era of it. Yeah, it technically started in 59, but by the end of its run in the sixties, it was already of it the greatest shows in TV, period. Every credible list of great TV includes it. Again, it isn't fair to call it a sixties show since it would return in other decades, but the episodes that comprise the original 5 season run in the sixties can stand up to anything from any decade.

And that's just dramas. The sixties had some of the best sitcoms, and some of the best variety shows as well. Hell, variety shows were all over the place in the sixties lol, but the quality of those is great.

But what you said is why this kind of thing is often impossible. There's just so much bias in "best of" discussions because it's inherently subjective unless you find a way to step outside of what the individual likes and expects. To get there, someone has to have spent a shit ton of time watching shit from every era. A lot of TV watching. Even us eighties kids that were half raised by TV sets don't usually have that much time in unless we're also TV geeks to an extent. And you'd still have bias and subjectivity, just more informed.

Hell, I'm making the argument for the sixties, and my actual favorite shows ever aren't from the sixties lol. I'm still biased towards what I was most exposed to.