Most people prefer raw input on
If you have it off you'll probably have mouse accel.
Though not inherently a bad thing it messes with the aim of a lot of people. Especially if your ingame sens is already high and you flick a lot
If you don't like the feel of raw input you can try this accel driver. Being able to tweak the accel settings can help you find a good compromise if you feel the default mouse accel nor raw input suits you. It's most common use is having a relatively low sens but with some accel so you can track easily with low sens and still flick/rocket jump when you need it because of the accel