I've had a couple good ones. I usually hire them when the kids are infants and toddlers that haven't gained enough movement skill to go help themselves to food. One of my favourites was a random townie named Angel who has the Hates Children trait. She was hilarious.
Because the highchair can be buggy you still have to keep tabs on them but it helped keep the little monsters fed and the house a bit cleaner. Pretty much guaranteed to increase your adult Sims friend count too, those Nannies are wild on their nights off! Hahaha