Switches and Switch testers
Switches are the rabbit hole, but the first decision is simple: linear for smooth speed, tactile for a bump you can feel, clicky only if everyone nearby has agreed to the noise, and silent for shared rooms.
Then check force and travel. Light switches feel fast but can cause accidental presses; heavier switches feel controlled but can tire some hands. If you are still guessing, a switch tester is the sensible move before buying a full set.