Kanban board to drag and drop cards across columns. Select which group type to show as columns: status, milestones, labels, teams, etc (you can create your own dimensions) Set rules to your group (such like auto-assign card to user when dropping a card)
Cards can have checklists. Items in the checklist are actual cards, which can be organized in their own board. Projects is like a tree of card, with unlimited sub-level boards. Perfect to manage complex project with hierarchy. You can choose different settings and user permissions at every level.