- Gi Joes (and other 12" figures)
- LEGO
- Matchbox or HOT WHEELS (etc)
But I would almost surely put LEGO at #1, if I had been a kid anytime since about 1990; though Hasbro did give the Joes backstories, personalities, etc., since shrinking them. Not to mention better vehicles; but the creativity of building sets almost surely tops the GI Joes, regardless of what accessories, etc. they might have.
Still, my absolute favorite 12" figure is MARX Mike Hazard. A friend had one, & when he outgrew his, I begged it from him. James Bond could not have more spy goodies. Exploding attache case (used one cap from a roll), also had knife in its side, just like Bond's in From Russia W/ Love. A Luger with removable barrel swapped for a sub machine gun, wigs, glasses w/ beard, cool stuff.
I still have it. 
The odd thing about this figure, is that MARX never made an enemy for it. In the medieval knights & Johnny West series, there were the heroes and villains. But this guy was all alone.
One Christmas, I got a GI Joe Desert Patrol attack Jeep, modeled on TV's RAT PATROL. ALL IN ALL, I had 4 similar jeeps, 2 of these (begged the 2nd one off a relative, who had grown up). The mother of that family made great pan fried chicken! The friend mentioned earlier, had a green GI Joe jeep with cannon (that shot a plastic shell, & trailer with searchlight. Some Xmas, or was it a birthday? I also got one of those, but, safety-minded busybodies forced HASBRO to block the barrel, so it could not shoot the projectile!
I painstakingly drilled out the rivets on the cannon, opened it, and filed out the blockage.
The 1st jeep was a Stony Smith SEARS exclusive. I do not believe it lasted very long, though. The Marx figures lost their ability to hold a pose after the notches inside the joints wore away.
As I hated everything about myself, I hated figures' light colored hair, & took black markers to color their hair more to my liking, but often slipped. Thus, few would want my collection of them.
LEGO back then, was rather boring, at least compared to current sets. Nothing much moved, though there were a few pieces that did. No minifigs, no, not for several decades. Still, building things was fun.
There were two electronic sets: One made by Raytheon, as I recall LECTRON, AND A radfio shack 100 in 1 set, but I had very little, if any understanding of electronics then. I did turn the so-called lie detector into a shock box, using a separate switch, and the set's relay, though I doubt if I understood how or why it worked.
Oh, Matchbox, HOT WHEELS & JOHNNY LIGHTNING. I had a JL https://en.wikipedia.org/wiki/Johnny_Lightning track that used sliding levers to catch hooks underneath the cars, & fling them forward. Johnny Lightning - Wikipedia. It did not last very long, though.
I had at least two slot car tracks, the 1st one had the 1930s style cars and a figure 8 where they were to collide. Fenders would fall off, etc. Not an HO scale, likely several times larger.
hmy: It looks like an optical illusion!
(Fortunately, most people simply assumed that me being female meant that sports questions would be too difficult for me. 
