Is there a website that is kind of like Similarworlds but better and more active?

Quora. Users ask questions and other users answer. You can also comment on answers. Quora has a huge amount of action, way more than here. It's also a different vibe because you have to use your real name, and they have a strict "be nice, be respectful" policy, and will kick people off for violating it. It tends to be more erudite and mature as a result.

You also have a lot of subject matter experts; for example, if you ask a medical question, more than likely, a real doctor will answer. I asked a question on criminal law, and was answered by a past president of the National Association of Criminal Defense Lawyers. Quora is like SW for adults.