I love your quilt!!!
My advice is going to be a little different than others, I think. SID and FMQ can both be quite difficult for some of us. I quit doing traditional SID because I am a perfectionist and found it nerve-wracking trying to keep the line exactly where it was supposed to be (which I never achieved anyway). FMQ took a lot of practice for me.
My advice is to quilt over all the seams, but with a narrow zigzag stitch, a serpentine stitch (looks like a continuous S as it stitches out), or a decorative stitch. These stitches have some width to them, so slight deviations to left or right of the seam do not catch the eye at all. They are a much more relaxing way to quilt than SID or FMQ, in my experience. Experiment on a sample first. A lot of decorative stitches are awfully slow and take a lot of extra thread and may not be worth it.
Since you have such a geometric quilt, I would probably choose a narrow zigzag (not a satin stitch!). On my machine a stitch length of 2.5 and stitch width of 1.5 for the zigzag looks really nice. I just completed a colorful charity quilt using this zigzag on all of the seams and diagonals, and it turned out really nice. It's not traditional, but it's *very* sturdy! Charities for kids often prefer machine stitched binding for durability, so I used the zigzag to finish the binding too.