Playing something like UT or Quake, and so many more FPS benefit from the rapidity of the mouse, but timesplitters there's no other controller than the PS or Logitech dual joystick controller (which controlled that sub that imploded recently).

First person or shooter games I use mouse and keyboard for better control. I couch PC game so it's actually a wireless trackball and keyboard I use. For anything else it's controller.

i use controllers for RTS games on pc. one stick to scroll the map, other to select units. my wrists are too weak to use a mouse for several hours

Really depends on the game. I usually get a lot faster and more precise adjustments using KBM, so I prefer that for games like shooters and anything where precise 3d movement or fast reactions is an issue.

Basically the only games I play with controller are the ones that are really well optimised for controller and kind of meh for KBM and the ones on my Switch.

I prefer controller on all games aside from top-down games and competitive games. Even faster games that I treat more casually, like destiny or overwatch, I use a controller.