I buy very few of the "Leap Frog" type educational toys. I think kids need to learn through experience, not by having a computer voice drill them. I buy lots of toys that require imagination and problem solving skills; things like blocks, craft kits, role playing toys. I also like outdoor or active type toys like hula hoops, sports equipment, etc. We buy TONS of books. Now that my kids are older (5 and 7) they prefer science stuff. My son likes Matchbox cars and superheros a little but my daughter was never into Barbies, princesses, etc, (though she does like stuffed animals). Both really like the experiential type toys we have and even choose to buy them with their own allowance.
They like going to their friends' houses to play wii. But their friends like to come here to cook, explore the outdoors, and do craft projects!
Bubbles, balls, and slides are not "just toys!" All three teach basic physics through experience. Slides and balls help with coordination and physical development, including equilibrium. They can all be used for make believe. Stress management and "just plain fun" are important life skills, too.