All of your childhood cartoons 
I don't know. I don't think when it comes childhood cartoons I'm that nostalgia ridden. I mean I've tried to watch X-men TAS and yeah that hasn't aged well. Rugrats, well that got pretty bad even when I was a kid.
I think Beast Wars holds up as a toy commercial with some solid storytelling. Batman TAS is still pretty great. Pete and Pete is still a pretty good imaginative live action kid show.
I mean stuff like Power Rangers is hard to take seriously after your what 8? I think most Nick stuff got pretty terrible later in the 90s. I don't know must kids shows I don't think I could go back to. I mean I loved toonami, but Gundam Wing is pretty terrible and funny to watch. I got over shonen shows pretty quickly. I don't know, I can't even think of a lot of kid television I watched anymore. Lots of Nick stuff that I couldn't watch at all anymore. Hell around 12 I stopped watching most nick stuff. The Live action stuff is of course a no go.
But I do think Beast Wars, Pete and Pete, Batman, Daria(if it counts, but it actually got better as I got older) and some toonami stuff are still pretty watchable.