In "Controls":
First person control type - Standard FPS
First person look-around sensitivity - (your own preference but mine is one down from the middle).
First person aiming sensitivity - All the way down. (Ill explain why in a sec).
First person aim/look deadzone - All the way down.
First person aim/look acceleration - All the way up.
Auto level Camera - Off
Field of view - (Your preference although to me, putting it to the lowest makes it feel more like BF or COD)
Head Bobbing - Off
Some reasons for these settings:
• Standard FPS makes the controls switch to a normal fps game with tapping R3 making you sprint and so on.
• The reason i set aiming sensitivity all the way down is because in almost every shooter, when you aim down sights, it gets a lot slower when you look around to make it easier to aim. Putting aiming sensitivity to the bottom does the same thing in GTA and with the looking sensitivity higher than the scoping in sensitivity, it will make it feel more like a proper FPS game.
• In short terms, setting deadzone all the way down and acceleration all the way up, will just make it more snappy and responsive like again, any other FPS game.
• Auto level camera off, just makes it so the camera stays in what ever position u leave it in, even when you are moving.
• Head bobbing off, just makes it smoother and less "bumpy" i guess is the right word!
These are just what work best for me anyway
Play with the settings more and find what is best for you!