好玩儿 (hǎo wánr) means 'fun, amusing' and specifically describes an activity, toy, or place that is enjoyable to play with or experience—it emphasizes playful fun. 有意思 (yǒu yìsi) is broader, meaning 'interesting' in a thought‑provoking or engaging way, and can apply to people, ideas, or conversations. 有趣 (yǒuqù) is more formal and often used for things that are fascinating in a less casual sense.