It's not about preference, but about being able to see the differences in the first place, so any sufficiently contrast combination should work.

If you turn on the color filters in accessibility settings in macOS you can see what the contrast could look like to a colorblind person.

You're not gonna believe it but NONE colors, my brain doesn't process colors because I know I cannot trust them to be correct. So I use shapes, numbers, arrows.

Ask a colorblind person to explain how to win at candy crush and you'll be surprised (hint: we do not use colors, we use the shapes).

I don't have any color discrimination deficiencies, but it is my understanding that for various types of signage, the move has been towards RED=bad/danger/etc, and BLUE (instead of green)=good/safe/etc.

For color deficiencies, different lightnesses are safe e.g. dark for loss and light for gain (could be dark reds for loss and light greens for gain, but don't mix the lightnesses). Other options are icons/shapes (like up/down arrows) or pattern fills (like stripes for loss).

The general trick is you can rely on differences in color lightness, patterns, text and icons, but not differences in color hue. The page should be usable in grayscale.