Favourite skill?

Robotics, Fabrication and Archeology have to be my top three, so much to explore with these three skills.

Writing is my favorite. I love deciding what kind of writer my sim will be and what their books will be about. I had a romance writer who wrote biker and steampunk romances and Rohan Elderberry wrote a biography on Felix Psyded.

Edit: he's also a poet.

archeology and selvadorian culture

Herbalism.

I always enjoy having my Sims dance. They usually sing as well.

Violin is my favorite skill, its my fave instrument and Im so glad its in the game.

Additionally, I download delicious CC food, drinks, desserts and whatnot. YUM! Gotta make up for what I can't do IRL due to health issues.

I tend to have Sims in the creative arts; painting can be quite lucrative (especially now with Plopsy), and if a Sim completes the Painter Extraordinaire aspiration, not only can they paint all the emotional paintings regardless of mood, they can write all the emotional books (Playful Book, Romance, Sad Book etc.) when they reach the right level and carve all the emotional woodcarvings regardless of mood, so it might be one of the most useful of the aspirations. (It's also one that technically can be finished before a teen ages up to YA, at least if you play on Long lifespan.)

Gardening is definitely my favorite. I don't care for the flower arranging, though.
Handiness is also one of my favorites.

I had to go with the musical instruments. I love hearing their playing improve from ear-shattering-screeching-car-brake to Itzhak Perlman bringing people to tears with the theme to Schindler's List. The difference between levels 1 and 10 is so stark, and there's an audible and visible improvement with every +1 in skill. Other skills may be more rewarding in the Simoleons department or for other practical reasons, but to me, instruments always win out for being the most rewarding.

I like the Singing skill for the same reason.