My sims might choose a specific sport as a hobby or use it as their go to choice to raise fitness, such as cycling, workout videos or swimming. For mental health they might have a preference between meditation, journaling or going on walks with their dog.
For more cerebral sims they might choose cards, scientific studies (microscope/observatory) or reading logic books, rather than chess (unless required for aspiration, etc.)
Pub games like darts/foosball/Don't Wake the Llama from GT, ping-pong/robotics from DU, horseshoes from OR, bubble blowers from CL, collecting fish (especially endangered ones if Evil) for the aquariums from SD/DO are other potential hobbies and wouldn't suit every sim.
Building sand sculptures is one that can be done in most places and by most ages (by adding sand terrain paint as a sandpit, or just sandy areas like OS/SV/BB/WB) as long as IL is installed.
Painting, music and writing all have genres/styles. I often stick to one category once it's unlocked to further add distinction between sims. For writers you might get a famous sim who is known for their self-help motivational books, or romance novels written by that rather promiscuous sim (all the woohoo is just research, right?). Rebellious/deviant sims might stick to graffiti and defacing other's murals, whereas an outdoorsy painter might prefer landscapes.
They might have preferences when cooking and eating out too. Maybe they cook fish a lot to use up what the husband brings home on his fishing trips. If they are athletic they might not worry about their weight and thus cook more sweet treats. Maybe the family is Japanese (or other ethnicity), so they want to learn all the Japanese recipes.
Charity/community work is another option as a hobby, especially for sims with the Good trait. PH gave the option to volunteer with family via the phone. CL allows protesting via Politics career (unlockable for all sims with mods). IL lets you participate in beach clean up and beachcombing for trash. You can make community garden (food plants) lots to help maintain (don't forget bee boxes or bug houses as other sources of sustainable food). BG allows donating to charity on the computer. GF allows donating objects to fans and throwing fundraiser events (Good Reputation + Fame). BG allows skill mentoring and helping with homework, DU adds tutoring options for students. Seasons added the ability to gift items or money to other sims, so you can do direct donations this way too.
Throwing parties can be a hobby for some too. Whether it's high brow dinner parties and black and white bashes for your Snobs, or casual cookouts and costume parties for your suburban families.