Ask HN: Your favorite cross platform organizational tools and apps?

Hello HN! Looking for input for cross platform organization tools and implementations for different platforms. Trying to organize and optimize my work spaces for better focus and project prioritization, knowledgebase, reading list storage etc. What are your favorites, why do you find them useful, what are some drawbacks? Open to any input for both mobile and desktop platforms, currently working within Android, MacOS, and Windows. Thanks in advance for any feedback.