My favourite sim in my household is my heir, because she does interesting stuff (like the firefighter career, exploring tombs and getting kids). Emotionally she's not one of my favourite sims, I can't say I feel overly connected to her. She's a bit too perfect for that. I always have a weak spot for people with weaknesses so I often play those, which is why I decided to make her a stable, strong and straightforward kind of person for a change. Her only weakness so far is getting pregnant unplanned twice, from men she isn't in love with even. Which is a bit unlike her because she's a planner. I like teasing my sims :p
p.s. Since chatting and elaborating is one of the goals of this topic, I'll just repeat the same question for others.
Describe your favorite sim in your current household