FOV: 100
Sensitivity: 140% (This solely depends upon your mouse)
FOV hasn't really helped me see better but I personally think that FOV is just for aiming, especially for the bow. From my exprience FOV has only helped me become a better bow user.
Sensitivity is used to give you a better connection and feel with you mouse so you can actually
feel the movement and make your aim precise, it's hard to explain but it is kinda true...derp
Both of the things are trial and error, the user needs to find his own unique comfy spot :3