Kandor was an interesting concept. A miniaturized city in a bottle that Superman could have non-powered adventures in provided plenty of story ideas. My only problem with it was that it really made it hard to still think of Kal-El as the last son of Krypton. Supergirl and the Phantom Zone villains were one thing, but now there was an entire city of Kryptonians still alive and thriving? So much for the being sole survivor of a doomed planet! Perhaps that issue was dealt with at some point. At any rate, I didn't let it bother me too much, because I enjoyed the stories that took place there.
Superman and Jonny Quest first met in STF #3369...
Coming tomorrow: STF #4200!