VSCode (or whatever editor you use) is the most underrated design tool 😅 There's an enormous amount of design that happens in frontend code. That, and Figma 🖤
It really depends :). For design and prototyping, I use Sketch App on Mac, and lately Affinity Designer on my iPad Pro. And from time to time Adobe Photoshop and Illustrator for others (icon, photo editing).
For developing, of course VS Code and this is definitely something I can't live without. If you ask about UI framework then TailwindCSS is the first choice :)
Depends on the kind of project and stage of the project but daily I use these a lot:
Adobe XD
Github (for conversations on issues)
Notion for research and documentation
I've used lots of tools before, illustrator, balsamiq, figma, sketch etc. but the best design tool doesn't have to be techy, paper and a pen to sketch, a team for conversation/collaboration is very, very useful :D