What settings do you think a game absolutely needs to have, no matter what type of game it is or what specialties that game had. These could be game play or graphics or audio or even settings that fall out of these catagories!
mouse sensitivity adjustment, and all resolution options
It should also have full audio control for every type of audio in the game aka music, FX, dialogue, etc.
Any shooter game should have the option to hold or toggle ads (and maybe crouch). I only ever hold down RMB for ads and toggle for crouch. Some people may prefer different, but it just bugs the hell out of me when i can only toggle ads.
Rebindable keys.
Full audio control and rebindable controller buttons. Most games have rebindable keyboards keys but only a handful of games allow you to set your own controller buttons.
FOV
FOV, Resolutions, Rebindable Keys, Ability to turn off Mouse Accel and a button to make PC Gaming Master Race appear on my screen.
Saturation, gamma and brightness havent been said yet.
Gamma/brightness, inversion of mouse/game pads, subtitles, and maybe some volume controls. I think this covers the ESSENTIALS.
Low mouse turn sensitivity in-game, and high DPI mouse settings: Always for me.
has to have: intuitive default settings. i.e. be playable from first install.
other: some kind of basic screen calibration... e.g. i think the first resident evil in playstation had that back in the day. it was so you had the brightness where the shadows weren't entirely visible. made the game more atmospheric and the surprises more fun.
V-SYNC on/off.