Jira
Although Jira is typically a product management tool, design and dev play a crucial role in shaping user stories, making it a shared responsibility in some organizations.
Powerpoint / Keynote
As funny as it may sound, these were tools 'back in the day' often used for information architecture and flows.
Azure
Miro
Although this is not my primary tool… it is a very close second! I usually jump on Miro when teams prefer to use this (much easier for licensing for non designers team members).
FigJam
FigJam is my go-to tool for everything from brainstorming ideas, mapping user flows, and collaborating on early concepts.