This is less about the overall usefulness of each skill, and more about how much fun you have building them with your sims, be it because you find it interesting to watch them while they're at it, or ...
I'm irrationally attached to the logic skill even though it's not really that exciting. Archeology and pipe organ are pretty fun too. Least favorite ones? Fitness is a bit dull I think. Baking is fun but a bit too slow.