Betweens are too short for me to handle. I use John James "sharps" size 11. They are long, thin, and small eyes. I use waxed hand quilting thread made by YLI. I also use a very thin batting to hand quilt: "Quilters Dream" size: Request, 100% cotton.
Your quilt is made of bold bright colors, it could easily handle the big-stitch look with pearl cotton.
No matter which stitch you choose, do not skimp on the cost of very very thin batting that is easy to hand needle. The wrong batting will make your life difficult with every stitch.......