I have used embroidery thread on top and regular weight bobbin thread. I usually pick one color that looks good with all the pieces. I did a heart table runner and used bright red to outline the hearts, then quilted the rest free motion with white thread.

I leave all the stress of what type thread, what color, and how to quilt it to the show quilt makers. I pick a thread I like, use a bobbin thread that matches the backing and start quilting. I call my style Ever which way the needle goes. I have no plan or guide I just quilt. If my machine quilts without tension or thread issues then I nailed it. It's a good time and more then once I have surprised myself with some darn good quilting. LOL