Linear with old hybrid produces the most convincing (CRT like) scanlines but the gamma is too high (dark image).
Multiplication will have more correct gamma but the scanlines do not vary with brightness enough.
As I understand it, scanlines with variable thickness is essential for a convincing CRT look but the gamma curve should be fixed in the active part of the image (not the black lines).
Maybe a different approach is needed for this?
1. Create a convincing variable scanline thickness.
2. Fix the gamma curve of the final image with a simple reverse gamma function: y=x^(1/a) where “a” is variable and normalizing the output to peak white.