IME hamsters are OK, but a bit dull. They are nocturnal (IIRC), need to be kept on their own, and they smell.
Gerbils, on the other hand, can be kept in a pair, are active during the daytime and cause little smell (desert dwellers, so dry poo). They dig tunnels too, and if you want you can fill an aquarium with straw and peat so they can dig a proper tunnel system. Much more interesting, particularly to older children.
If your little one is very little a hamster might be more robust to indelicate handling however…