My favourite aspiration is knowledge because as soon as a sim gains a skill point, the sim always wants the next level up - so keeping them happy is usually easy especially if there are fun objects to help them gain skill points!
I also like the choice of careers for knowledge sims too - Mad Scientist, Education Minister and Criminal Mastermind.
I enjoy playing Romance and Fortune sims too because it is quite easy to keep them happy by fulfilling their wants of flirting or making money.
I don't enjoy playing big households of five or more, so Family sims that have a lifetime want of 10 children are a no no!
I have only played an occasional Pleasure sim, but aspiration points are low compared with the others, and I found it difficult to keep the sims happy.
I haven't played a sim with the Grilled Cheese Aspiration - something to add to my list still to do!