Linear

Linear is a task manager that shuns bureaucracy. It's fast (one of the fastest apps I use), with shortcuts for everything and a clear opinion on how to organize issues, cycles and projects. That reduces the friction of keeping it up to date.

For working on product as a system it fits well: cycles impose a realistic rhythm, projects group the scope, and views filter effortlessly. The roadmap stops being an aging PowerPoint and starts reflecting the real state.

It's opinionated, and that isn't for everyone: if you want to customize every flow, you'll feel boxed in. And it's geared toward software teams; for very general-purpose management it may be overkill.