The yellow is my choice

Beautiful quilt.

Definitely the yellow!!!! Black/white/and poison...love it!!!

Yellow.

Beautiful quilt! I think the yellow sets it off, as the complementary color to purple, but either narrower (piping, faux piping, flange, peeper) or just a shade lighter. It comes across on my monitor as so bright it overwhelms the whole, but the same hue in a tad lighter shade would be more mellow while still giving a hit of zing. Shifting to the light lavender instead of the white would also be a good option.

Yellow pulls the eye away from the quilt itself. Any other border would be my choice. But it's your quilt.

I go with the yellow because it makes the whole thing just pop.

2

My vote is for #2. Since there is no yellow in the quilt, warrant
it brightens the quilt, it still looks out of place. The violet is softer against the dark fabrics and makes more of a contrast between the quilt and outer border.

Yellow. Makes the rest of the quilt POP!