ToDoCloud
I have been using ToDoCloud for more than 10 years since before it was ToDoCloud. I use it to keep both my personal life and my work life organized. Its array of lists, smart lists, tasks, projects and checklists provides for extensive tracking of task. All items can be dated, timed, prioritized and tagged. The search function is inclusive. Appigo support has been very helpful on the couple of occasions when syncing failed me.