I usually go for simunity first. I just find allergies/illness annoying and want them gone. Plus, as someone else mentioned, it's a cheap reward.
Second for my adult sims is likely long-distance friend, and for kids it will usually be fast learner. Not too into the ones that slow needs, probably because I gave my very first athletic sim the one that diminishes the need to sleep, and his working out ALL THE TIME made me crazy.
Things like extra creative, or whichever like it that fits what my sim is/does, usually get picked up eventually, and I like someone in the household to have a collection helper, which often gets passed to the next generation.
@Odonata68 I didn't know what inappropriate in a good way does. I have to try that out!
