Actually, my favorite toy when I was preschool to about grade 4 was a set of blocks. We built everything with them, including marble runs, mazes for the cat, knock-down towers (our mom hated those especially when she had a headache), Barbie houses, horse barns, and many other things. We also wrote on them for some reason, so many of them say “on the bee yes,” which is all my brother could write at the time.
We admixed the blocks with Lincoln Logs, Tootsie Toy cars, Breyer horses, dollhouse furniture, and some sort of plastic brick building set that wasn’t Legos but was similar.
The same blocks were passed on to all the grandchildren (mine and my brother’s kids) who also gave the blocks a lot of exercise.
Otherwise my favorite toy was the sandbox and a hose, a messy but enjoyable combination.