Variety just created a list of, in their opinion, the 100 best tv shows of all time and to my pleasant surprise I Love Lucy is NUMBER ONE! Here is the article if you want to check it out.
When TV Guide did a similar list some years back, ILL came in at #2, with "Seinfeld" at #1. As brilliant as "Seinfeld" is, I've always felt ILL is greater because a three year-old can be just as entertained by it as a retired intellectual (small kids won't get "Seinfeld", which also lacks common humanity).
Steven, as you may know, I'm not, like you, an admirer of Ball's post ILL TV shows, as I consider them majorly inferior to her breakout series. That being said, there are a few occasions where, say, The Lucy Show is equal to, or even greater than ILL in a single episode. For instance, the Christmas offering from the first season of The Lucy Show is hilarious (Viv wants a white tree, Lucy wants a green one, etc.). It is vastly funnier than the sixth season Christmas ep of ILL, which only gets laughs during the "memory" clips.
Yes, Seinfeld was a great show. But it won't have the longevity of ILL. Seinfeld used a lot of "current event" type humor. If the next generation of viewers is not up on what happened in popular culture from the 1990's, then they won't get a lot of the jokes.
Lucy on the other hand, was timeless stuff. Everyone can understand and appreciate marital squabbles, friendship arguments, greed, ambition, and just plain silliness.
It's not supposed to be about humanity. Jerry Seinfeld's rule was "no hugging, no learning". The show was just supposed to be funny, which it consistently was. "Seinfeld" probably was the best sitcom of all time, although I've seen every episode at least two dozen times and I'm currently burned out on it.
As far as "I Love Lucy" is concerned, I've never cared much for it, although I do like Ball in her pre-tv movie roles of the 1940s.