My children are older now, and their "toys" are quite different. Does an iTunes giftcard or a paintball gun actually count as a toy?
The things that have endured in our home have been the classics. We still have a container of wooden blocks that we pull out when we have little ones here. They have always been a favorite.
For our boys, we have seen sports equipment go the distance. They still think a football is an incredible gift. We never had a gaming system, but they loved the Backyard computer games, especially Backyard Football and Backyard Baseball. Any imaginary battle involved a light saber, so they still consider those essential.
Our daughter always enjoyed playing with Barbies, of course. She also liked to get craft kits which came with all the supplies needed for a project. These were great because they were consumable.
They all enjoyed their play kitchen and concocted many kinds of goodies there. We also had an indoor playhouse that got a lot of use for many years. It had a small slide on the side that was apparently tons of fun.
The cold, hard reality is that our children played with very few toys. Even as I asked them about this topic today, they were hard-pressed to recall many specific toys they truly enjoyed for any length of time. I honestly believe their best times were spent imagining great adventures in our backyard and building blanket forts or reading good books indoors when it was cold or rainy.