Well, the best is to try them : non-destructive editing means you can always step back to the import state with no quality loss, with the "Default" button.
"Auto" tries to guess which settings to apply ; like many contemporary tries in AI, it is more often than not deceiving I find.
The best is simply to go from top to bottom with the ACR sliders :
- adjust WB first,
- then adjust exposure to have the right rendition of highlights,
- Recovery may help with burnt highlights too,
- open the shadows if needed with fill light,
- adjust black point with Blacks (often needed after a significant Fill light adjsutment),
- shift the midtones to where they fit with Brightness,
- boost the contrast if needed now,
You still can go back and forth (eg, you'd want to have decently exposed midtones to fine tune WB), but I find this top-down approach quite sensible.