My favorite website to share with parents and caregivers is http://www.commonsensemedia.org. They rate shows based on their content:
Positive role models & representations
Violence & scariness
Drinking, drugs & smoking
and then also give a short synopsis of the show and give parents/caregivers a heads’ up as to what to look out for (for example, if there is a great movie that has one fairly scary part, they will warn you about it so you can prepare your child or plan to skip it if your child is sensitive).
Some of the shows they recommend for preschool/kindergarten are:
Luna Petunia, Storybots, Super Why!, Word Party, Beat Bugs, Earth To Luna, Bubble Guppies, Bookaboo, Super Wings, Peg + Cat, Reading Rainbow, Mr. Roger’s Neighborhood, Tumbleleaf, and Wild Kratts