The ones I use daily or almost daily:
a simple, scanable tab manager that lists all the tabs over all your windows in one list. you can close tabs via middle clicking them and bring the tab you want into the forefront by clicking on it.
an extension that captures capslock and a/d to cycle focus from one tab to the left or right
an extension that opens up a folder of bookmarks a few bookmarks at a time via a right click menu option
an extension to change the speed of a youtube video by having - + buttons at the bottom of the page overlaid and also tells you the current speed of the video.
an extension that made a few quality of life tweaks to the apple development docs.
a theme extension that fits what i want the browser to look like.
I have some others but these are the most useful to me
In meatspace, I built a fan box that hangs at the top of my window facing out so it can take the hot air from the ceiling and push it out while a fan at the bottom of the window pushes cool outside air in.