It used to be survival and rampaging instincts. Small helpings of logic and philosophy increased as the ages rolled and forged the human spirit. Planning and preparation, alliances and compromise and other complexities increasingly became parts of our lives. Sightsee the posterboards. Let them help you along the way.
Some toys are favorites because they inspire the imagination.
Dolls and modelling clay are examples. With other toys, it's the experience the toy provides. Speeding down a hillside on a sled or staying overnight in a tent in the middle of a woods, gives the sled and the tent a place on my favorite toys list. A toy might become a favorite by presenting a challenging task, you develop a skill to deal with the challenge, then performing and improving your skill brings a sense of accomplishment and self-esteem. For whatever reasons, these are my favorites.