For my own projects, Redmine or plain text to do lists. My customers are using / have been using these systems in the last ten years: Jira, Trello, Kanbanize, Y

For my own projects, Redmine or plain text to do lists. My customers are using / have been using these systems in the last ten years: Jira, Trello, Kanbanize, YouTrack, Confluence. The best balance for medium sized projects IMHO is Kanbanize, not too limited, not too complicated. For a single developer probably everything will do.