Very pretty quilt!
I would make the binding from one fabric, because using a scrappy binding may detract from the center. I would audition the border fabric and the red fabric first. I'd also probably audition a darker blue fabric similar to the one in the center with the black (?) squiggles - something like a tone-on-tone or marbled, something subtle.
I lay my audition fabrics under the edge of the quilt so just the width of a binding shows. I stand back to look. I take pictures. Sometimes I don't like any of them. Sometimes I leave it up for a day or two or three. One of the fabrics eventually jumps up and grabs me and says "I'm the one!"
