My Dad's TRS-80 Model III was the first I can recall using. I was about 3, and I like to press the clicky red reset button on it. I think he didn't enjoy that, as he was probably working on something at the time. A kid can be worse than a cat when it comes to computer interference.
The first I owned, as a gift, was a Color Computer II, with the game cartridges like Doubleback, and Megamunchers. Didn't do much computing on it. Then we got a Commodore 64 and Vic 20 parts. Never got the Vic 20 going, but we had fun with the Commodore 64. The school, where my Dad was a teacher had his Model III, and a Model IV, and a bunch of Apple ][, and ][e computers. Soon there was an 8088 as well.