I have a toddler and two older kids, so we see quite a lot. But there are definite standards of quality. Those who don't have to have them on at all think of them all as equally cruddy, but not so. My top ones, both current and retired, are as follows:
Curious George (good interpretation of the stories with humor)
Ni-Hao, Kai-lan (just so darned cute, and hardly any singing)
Charlie and Lola (again, cute, reminds me of my kids, and I love their little accents)
The Backyardigans (for some reason their songs don't make me want to scream)
Wordgirl (another one with humor; such as a man voiced by Peter Graves trapped in a vat of mayo due to a dispute over a sandwich)
Phineas and Ferb (a little older target audience so contains some references adults get better than kids)
Kipper (Just one of my favorite kid shows ever. Sweet and calming, and yet funny. Most kid's shows would teach that it isn't nice to get back at your friend for inconsiderately eating the last sandwich and bag of crisps by giving him the last soda, well shaken, and laughing at him when it soaks him)
Maisy Mouse (I swear I don't know what it is about it, some shows are so weird you can't look away)
Tokyo Pig (not sure whether this fits but we like it, strange yet funny)
Peep and the Big Wide World (funny show, we all like it)
Each of these has something that stands out, some higher quality, that outshines any irritating qualities they might have. I usually find shows with poor animation grate on my nerves, but in cases of ones like Charlie and Lola or Phineas and Ferb, the style is sufficiently "cartoony" that I don't mind it. There are also some decent mid-range shows, that aren't my favorites but have their merits. Yo Gabba Gabba is plenty odd, but is so different in a good way that I like her to see it sometimes.
My hate list is much longer. There are so many inferior shows on TV. The worst I will list:
Barney (sort of the gold standard for horrible shows)
Hip-Hop Harry (one in a long line of shows that try to promote something different and end up making it less appealing. Also among the kids shows that try to put on a "cool" face, and fail)
Wilbur (all about the love of books, supposedly, yet they never mention a single book that they didn't make up themselves for the show. An example of "ugly puppet" shows that design puppets based upon the dress and proportions of children without regard for how freakish the results will be when the subject is a bi-ped cow or sneaker-clad duck with HAIR)
Dora the Explorer (annoying little show with shrill voices and freakish and unnatural animation and not a drop of style to make up for it. There's a fox who steals for no good reason at all except spite, but once in a while he's suddenly nice. And I few, too few, Spanish words are taught. If they wanted to teach Spanish, I'm all for it, but go for it, instead of teaching the same words over and over. Still, this show is harmless and innocent compared to the more aggressive and offensive Diego)
Go, Diego, Go (Yes! Offensive, for they have the world's most shrill little white boy as the very South American (and badly animated) Diego, who feebly teaches a few more badly pronounced Spanish words such as "fest EE vAL!! !!" and who is surrounded by talking animals like sea birds who apologize for "accidentally" flying off with penguin eggs and such, or pumas who will hunt for the hiding tapir while completely ignoring the delicious and easy to catch boy standing and waiting to become lunch. Thus this show teaches a little bad Spanish and more tainted animal facts. And... it's my kid's favorite. What the heck, she's not likely to be around a talking tapir hiding from a puma)
Wonderpets (they're cute but dang it, they talk in recitatives! And where the heck are the parent animals? Yeah, I know, classroom pets that save baby animals. Reality is out the window. But still.)
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"Pack up my head, I'm goin' to Paris!" - P.W.
The world loves diversity... as long as it's pretty, makes them look smart and doesn't put them out in any way.
There's the road, and the road less traveled, and then there's MY road.