I would avoid most stuff that you loved as a child. Esp stuff like "Battle of the Planets", "Thundercats", "The Incredible Hulk", etc... Stuff that was a fond childhood memory is generally better left as fond childhood memories. A lot of it does not, hold up well to a repeat viewing as an adult.
Then there's the "projection" factor. I've noticed that with some series fans tend to project their hopes/dreams/fantasies onto series that had some interesting aspect and then ignore the cringe inducing stupidity and/or sillyness of the rest of the show. Usually these are also the ones that generate a lot of fan fic.
If you can watch a single episode of the series and not wince or recoil in horror then it might be worth getting. So rent disks or get netflix to test out old series, especially if they are something that you haven't seen in decades.
Then there's the "projection" factor. I've noticed that with some series fans tend to project their hopes/dreams/fantasies onto series that had some interesting aspect and then ignore the cringe inducing stupidity and/or sillyness of the rest of the show. Usually these are also the ones that generate a lot of fan fic.
If you can watch a single episode of the series and not wince or recoil in horror then it might be worth getting. So rent disks or get netflix to test out old series, especially if they are something that you haven't seen in decades.