My favorite to level is Cooking. It has a really nice visual progression as your sim gets better at it, and I love watching the animations for it all the way through, even during the mid-levels. It's probably the only skill that I don't try to fast-forward through building.
As for least favorite, Herbalism by far. On top of the fact that I have to take a vacation to get to the materials I need, scanning over the Granite Falls floor looking for plants and bugs to collect in order to level this skill irritates me and I don't find it enjoyable whatsoever. I know there are other ways to level the skill but they either take more time (like growing the plants at home) or feel cheaty (like getting the plants off the gallery or something)
