Well if we are going back to childhood I had GI Joe, Mike Power the Atomic Man, Captain Action with the cool superhero costumes (these were actually my brothers that I inherited) my favorites were Captain America and Aquaman accessories. We had the GI Joe's helicopter and undersea adventure set with the stinky rubber octopus. Johnny West, Zeb Zachery, Sam Cobra, and Geronimo as well as Odus and Eric the Vikings.
While not 12" or 1/6 I had an extensive mego 8" collection with Captain America as my favorite and Shazam a close second. I also had the star trek mego collection along with the enterprise with the spin around transporter. Action Jackson was another cool line with tons and tons of accessory packs, we even had the jungle tree house. Evel Kneivel with his stunt cycle, Big Jim with muscle band action, as well as Big Josh and Big Jack. Six Million Dollar Man, Maskatron and Big Foot.
Recently a toy store opened up near me carrying vintage toys and I was forced to realize just how cheesy most of these toys were, not that they didn't get the job done back then.