The right blue could look lovely! Because blue is not in the blocks, though, I would (1) add narrow blue sashing strips if you also add a blue border or (2) add a narrow strip of blue around the quilt before you add the brown border. You could then use either brown or blue for binding. In my opinion, you do not want to add just a wide blue border to a brown quilt; it will look as if the blue border was an after-thought. Incorporating blue in sashing strips as well as the border, or just adding a narrow blue strip to separate the quilt from the border would work well, though.
I'm not sure how the color wheel works but, in my opinion, blue would "set off" the brown and liven up the entire quilt.
Edit: Or stick with feline's recommendation. In this case, the quilt will look very nicely modern *and* neutral so it will complement almost any decor.