We use our own ticketing system that we built using osTicket. osTicket is an open source ticketing platform. It works for the scale we are at. It was an easy way to save a few bucks.
We like how really easy it is to see a snapshot of everything with Trello. Asana was a pain. We had to keep everything in post-it and notes and then import it into Asana. In the end, we decided to move away from it. In addition to these tools, we have our own agile development process.