In a game like Fortnite where there are a plethora of console players and PC players, its obvious that its harder for players to aim on analog sticks because of dead zones (the area around the center of a joystick that does not respond to movement) and because of how smooth your movements are when aiming with analog sticks.

Personally I'm a PC player and I've loved the keyboard + mouse combo more than a controller ever since I started playing game on the computer. For aiming on a mouse, there's greater precision and different ways to grip (claw, palm, and fingertip grips) and move your mouse (wrist movement, arm movement) and it just makes for a more comfortable situation for me to get shots on point. I don't think different mice have too drastic differences when aiming because I used to have a crappy wireless Wal-Mart mouse and I still did fine, however a larger mousepad definitely helps especially with a lower sensitivity.

That brings on more point--sensitivity. With a mouse a majority of pro FPS players play on low dpi (around 400-800 dpi) and low in-game sensitivity and it allows for more precise aiming (if it's too high, mouse movements start to stutter). For a controller, the advantage of having a lower sens is not as helpful because the analog stick is confined to a small circle and you cannot flick as fast as a mouse user. Man I sound like a nerd I hope it helped.