I'll just lay it right out there...
Curious George is the best television show for children (of any age).
It was the first show my daughter (about to turn 2) ever responded to, and it has held her attention and Imagineer since. The twist is, it's done the same for me.
From the first episode, it's fantastic. Each episode comes with 2 stories, usually alternating between the country and the city. The first story is an exciting adventure with George getting stuck on a runaway kite. It's very much in the spirit of the original books, but much more good spirited than the original stories. The second (and what sold me) had George investigating scratched restaurant booths to clear the name of his cat friend Gnocchi. Somehow the show effectively teaches forensics to preschoolers!
The show delves into educational content more seamlessly then I've ever seen. It covers STEM subjects, social interactions, friendship, personal responsibility, and simply rejoices in, well, curiosity.
If I keep going I might as well publish a book about how great this show is, so I'll sum it up with "that's your reward: you'll never be bored if you ask yourself, 'what is this?' like Curious George."