Theoretically white on black is harder to recognize than black on white. When you have the same font weight, the white on black approach tend to make people fe

Theoretically white on black is harder to recognize than black on white. When you have the same font weight, the white on black approach tend to make people feel the stroke looks thinner and more blurry. If you are curious you can switch to black on white, then adjust the font weight to the thinnest until you feel it starts to be blurry. When switch back to white on black it would be more blurry to you. But anyway it boils down to preference since people can adjust the font to compensate if it is blurry to them.