Arthur was always my favorite as a kid. What kept me loving it as an adult is how well every episode holds up and how brilliant and absurd the humor could be. In one episode, a kid's head falls out of the sky and compliments the lawn it lands on. In another one, a tiny version of Neil Gaiman is just chilling inside someone's sandwich. Both of these make as much sense in context.
For me, the mastery Arthur had over complex themes and childhood experiences was best shown in its autism episode. It's called "When Carl Met George" and while it dealt with Asperger's specifically (which has since been wrapped up into the Autism Spectrum Disorder umbrella, thanks to the DSM-V), it still explains what being autistic is like to children in a plain, easy-to-understand way.
For me, the mastery Arthur had over complex themes and childhood experiences was best shown in its autism episode. It's called "When Carl Met George" and while it dealt with Asperger's specifically (which has since been wrapped up into the Autism Spectrum Disorder umbrella, thanks to the DSM-V), it still explains what being autistic is like to children in a plain, easy-to-understand way.