Not staff anymore and you may already be aware of most that I'm going to say, however these are aspects you may be unaware of which could help you find popular topics. Hope they help :3
Blue = Shows recent popular topics
Yellow = Can be clicked to view brand new topics that haven't been viewed by yourself yet
Red = Is added by staff to designate important topics
Grey = Shows unread topics that can help you find which topics at the time are receiving the most new posts
You also have the 'Top' tab which enables you to sort topics by when they were created, categories, replies, views and activity. If you want to find a popular topic, that is probably the place to do so.