Personal and team task management - Remember the Milk also now works with Google Assistant, so it's possible to tell the Assistant to set up a new task, a reminder, or tell me about what is due and what is coming up. A native Windows app, integration with Zapier and IFTT makes this an invaluable part of our productivity suite.
Google Tasks is a much simpler task-keeping interface, and I use it for the most important tasks on my phone. It does not offer tags, priorities, or distinguish between lists/tasks. It does let me star tasks, but does not let me determine the priority levels. I can also move tasks to different lists, but they can be hard to manage if there are too many, so I generally do not use this feature. For me, Google Tasks is ideal for very simple "I need to write this down" type tasks that are of high priority. It is not a good brain dumping tool because tasks can easily get lost. This is more for those nagging tasks that I want to do and make sure there is an appropriate alarm for. It also integrates well with my Android home screen. However, when I have lots of tasks I want to categorize, or I do want to do more of a brain dump type thing, I think Remember the Milk is far better. I can have more control over priorities, tags, assigning tasks to others, and other robust features.