I love Upbase. I appreciate its focus on simplicity and clean UI. Even as they continuously add new features, they manage to maintain a simple and uncluttered user interface.
Of all the project management software I have tried, this is the one that works best for me; it has become my second brain. All the projects are organized in what is called "lists" in Upbase, and each contains tasks (with kanban and list views), docs, files, calendar, and chat. The organization is really easy and efficient. A "list" can represent anything you want, as they can also be easily organized by folders on the left panel: it can be a client, a specific project for a client, or even a part of a project if the project is large. I appreciate how "lists" themselves are so adaptable that they can be used for various purposes.
I also admire their daily and weekly schedule; I like being able to switch easily between different views. In the daily view, I can quickly see which tasks are overdue so I don't miss anything.
As I've mentioned a couple of times: I love Upbase!