What are you wanting to accomplish w/ the border? To square off the quilt?
I don't like either one because they don't add the "pizzazz" that this beautiful quilt deserves.
I don't like the tan because it is too close in color to the outside diamonds.
What would it look like to fill in the outside diamonds w/ the hexagons to "square off the sides" Then add the white color - maybe narrow (1.5 inches wide) and then the tan color.
Consider auditioning all the different colors in the quilt to the outside to see what the different combinations would look like. I am often surprised that what I don't think will work actually works the best.
Consider googling Grandma's Flower Garden quilt images and look how others have finished off hexagon pieced quilts.
Take your time - that is one beyond gorgeous quilt!