Silverhawks was way cooler than Thundercats. The Silverhawks were in space, they were cyborgs, and they had been specially assembled to fight space gangsters. That's awesome. It's like The Wire but with half-man, half-machine, bird people in space. The Thundercats can't touch that. Thundercats was just He-Man with cat people. That's not nearly high-concept enough. Even for a young mid-to-late 1980s me.
I remember the time my mom happened to catch a few mintues of Thundercats while I was watching it one afternoon. She decided that it was macabre and disturbing (I remember the scene she saw had something to do with Mumm-Ra and that guy with the drill head) and quickly decreed that I was no longer allowed to watch it. My mother very rarely made such proclamations so this should have been a big deal but honestly I didn't care that much becasue, even at the time, I thought Thundercats was kind of boring. I was mostly just watching it to kill time until Silverhawks came on.
My mother never saw Silverhawks but I'm pretty sure that if she had, she would have decreed that it was awesome and that I could watch it whenever I wanted.