I did some testing on various monitors today, trying different combinations of pixel_ratio, ppaa, and material.aa.

My proposal is:

• Keep the behavior where we use SSAA on non-hiDPI displays
  • Well, actually fix/improve, see Rename alpha-method 'composite' to 'blended' #1172
  • It gives a good baseline for preventing aliasing for any object.
  • It seems 'fair' / consistent; the internal texture size is more or less the same, regardless of the monitor being used.
  • People can set renderer.pixel_scale=1 if they want to squeeze performance.
• Enable ppaa by default.
  • It's cheap and helps a lot to get a smooth result.
• Disable material.aa by default.
  • It does not improve the result much if the above is used.
  • Except perhaps text, where slight variations in the perceived width of the stems of am H can stand out.
  • I'm still on the fence between enabling aa in text by default, or simply enabling it in all examples and docs.
  • Though tools that work in 2D like fastplotlib should probably enable aa on objects, because it's cheap.