1. Masters of the Universe
He-man and the master's of the universe featured such an awesome mix of fantasy and technology it blew me, and most children at the time, away. The variety of bad guys, (Skeletor, Hordak, the Snake King) was so diverse and colorful. The molds for these figures were very similar, but for some reason that did not matter much to me. Articulation was very good for figures of this period, and the storyline was such an obvious good vs evil that it was too good to pass up. It's basically Superman drops into the Lord of Rings. Pretty brilliant if you ask me, and the figures are the best toy line of all-time.
2. Battle Beasts ( http://www.toyarchive.com/BattleBeasts/BattleBeasts1.html )
Some people are unaware of Battle Beasts. They are so close to being a better toy line than MOTU. These little animals, dressed in technological armor, and armed with crazy sharp weapons like modified axes and blades kicked some serious ass. On each of their chest was one of three symbols: fire, earth, or water. When you rubed the logo with your finger it would appear. The sculpting and design for these smaller figures were some of the best of its time. Not to mention really impressive paint jobs. I consider these figures to pass the test of time as Battle Beasts are some of the most extremely innovative and exciting figures ever created.
3. Teenage Mutant Ninja Turtles
When this cartoon hit the television I was sold. I'm still in love with how creative the idea of teenage mutant ninja turtles are to me. I will be a fan for life. I also was huge into the toys and video games. I also entered multiple create your own ninja turtle contests as a kid, but never won. But beleive me, my mutated elephant was pretty bad ass.
I will admit the current movie exposure has killed a small part of my love of this toyline, however, it is still one of the most impressive toy lines ever created. The early metal versions of transformer toys were simply killer, kind of difficult to transform but very solid and practical. Plus, they looked amazing.
5. GI Joes
A classic of course. I did not enjoy the 12" figures, I preferred the smaller and more intense figures. Some of the large vehicles and bases were the most ingenius of all toy bases. As a child I could not get over all the weapons and neat accessories that would come with each small figure. I was in love with the figure that came with a wolf, and also had a guy that came packaged with an owl. I didn't follow the cartoons or story very much, so I do not recall names. This toy line was so diverse and impressive. I'm pretty sure buried in my parents lawn is a number of plastic guns and figures I've lost over the many massive battles that took place there.
6. Army Ants ( http://en.wikipedia.org/wiki/Army_Ants_(toy_line) )
The little orange and blue guys are endless fun, with removable and interchangeable squishy tails, exchangable weapons and really cool sculpting. Articulation was next to none, however the soft plastic kept the figure from breaking. I did manage to lose almost all of the weapons over time. I will never forget the back of the blister card, which showed all the available army ants to collect in an ant farm maze. One of my favorite blister card designs of all time, unfortunately i couldn't find an image to show you.