
(Click for general game info.)
System requirements:

Latest drivers: (as at 21/12/2017)
Nvidia: 388.71
AMD: 17.12.2
Intel: Depends on your processor; download the driver update utility
Tips and tricks:
Benchmarks (NV), settings comparisons, and recommended settings (NV): See Nvidia's tweak guide.
Various CPU/GPU benchmarks and data: See this GameGPU article.
Note: The article is in Russian, but the data is presented via graphs.
Cap the framerate/potentially improve frametimes: Download RivaTuner Statistics Server, input your desired framerate limit in the "Framerate limit" box, and hit enter (the program comes bundled with MSI Afterburner and earlier versions of EVGA PrecisionX). Alternatively, those with an Nvidia GPU have the option of Nvidia Inspector, which can also be used to impose a framerate cap, either in a similar manner to RTSS or by way of forcing a different vsync interval (click the small tool icon to open the game profile section).
Note: Useful if you your system can't maintain, say, 60fps and you're sensitive to the wild fluctuations, or you're experiencing uneven frametimes. The greater window the engine has to render a given frame, if you're imposing a lower framerate than the game can otherwise provide, may also help in alleviating stuttering related to data streaming.
Stop the game from crashing after 15 minutes on touch-capable systems running Windows 10: Open the task manager, switch to the Services tab and disable TabletInputService.
Mitigate stuttering: Play the game while Steam is running in Offline Mode. (Credit to Ilive1up.)
Actually enable anisotropic filtering: Force it via your GPU driver control panel. (Credit to EatChildren.)
Enable RTSS' overlay: Follow the instructions here. (Credit to ClaptoVaughn.)
Run the game in a borderless window: While viewing your Steam library, right-click on Just Cause 3 -> Properties -> Set launch options... -> input /windowed /borderless -> OK. (Credit to Cannon Goose.)
Skip the intro: Download Rick's No Intro mod from JustCause3mods.com (Credit to electroflame.)

Graphics settings:
Fullscreen: Yes/No
Vertical sync: Yes/No
Anisotropic level: 2x; 4x; 6x; 8x; 10x; 12x; 16x
Resolution: Self-explanatory
Anti-aliasing: Off; FXAA; SMAA; SMAA T2x
Gamma: Self-explanatory
Texture quality: Low; Medium; High; Very High
Water detail: Low; Medium; High; Very High
Water tessellation: On/Off
LOD factor: Low; Medium; High; Very High
Shadow quality: Low; Medium; High; Very High
SSAO: On/Off
Motion blur: On/Off
Edge fade: On/Off
Global illumination: On/Off
Screen-space reflections: On/Off
Bokeh depth of field: On/Off