The Speak & Spell is pretty obvious. I played with mine from the age of 4 until 8. I rigged it to alternate power sources, I toted it everywhere. It is no wonder I later became a writer. I spent my childhood staying inside and spelling shit all day.
The only difference is that my Godzilla figure shot its fist off with eye-blacking power, and his other hand was replaced with red missiles that were best launched with a trajectory leading them to my toddler brother's head. I have no idea why this toy had rockets for one hand, or what sort of bizarre marketing that was, but I loved the thing.
Painter plays with Hot Wheels cars. That's his thing, for now. We've got a thousand, at this point.
And when he falls asleep, I play with the Hot Wheels cars.