I played so much Missile Command and Super Break Out on that controller, I got one of the 2300 TV boxes and that just didn't hit my nostalgia buttons because the self centering didn't feel right to me. At some point I hope to get another 5200 and some games, my original one fell off a shelf and broke when my father threw a tantrum and slammed a door.
Definitely the 2600. I may be biased, as it was the first true console I had as a kid. But you're right, in terms of impact, it has to be. It totally smoked the Intellivision and Coleco in sales. It also gave us Brian Cranston and Jack Black
If Atari hadn't been responsible for the video game crash and had been a little more realistic about the Jaguar, they may still be around as a fourth contender in the console wars today. It just seems like toward the end, everyone kinda lost their minds when marketing the Jaguar. It was just way too overhyped and way too underpowered, but they all acted like it was the hottest shit on the market.
I had a few games for the Jaguar, Alien vs. Predator was so much fun. I'd have to go with the 2600. My father brought home pirated games in the mid 80's so our collection was stacked.
I like a couple games on the Jaguar and find the hardware interesting; but the 2800 has the best catalogue. Pong is great, and I even have one... But uh... Can't play it for fear it might start a fire because that fucker gets hot and still has all the original parts.