[Crazy Jetty]

Welcome to the board!

While I do consider waterguns and weird rubbery balls to be toys, I too dispute them being "greatest toys of the decade."
Koshballs are only memerable because Rosie O'Donnel loved them so much, and used them constantly on her show.
My personal choices, and are both biased and pure personal opinion:
Exo*Squad- An extremely innovative line... the e-frames were amazing toys, and both human and neosapians were the most posable toys Playmates have ever produced... ever. I stress... EVER. (I'm harping on this because Playmates is in a pathetic state right now, since their new Trek toys were worse than the ones they produced in the fuggin' NIGHTIES.)
Star Trek- great posability, great sculpting (It's important to remember, most toys based on actors now use computers to create the actor's likeness on the toy. These were still hand sculpted), great character selection.
Jurassic Park- These are sadly the best dinosaur toys ever made.
Late Generation 2: This began the path we're on now, in terms of posability.

and above all:
BEAST WARS. 'nuff said.