The MSQ circle ruler is a good deal but it is only 1 size, if you are wanting circles just use something out of your kitchen. I use the interfacing technique - draw circles on interfacing, rough cut a little larger then stitch on the drawn line, cut a slit in the interfacing and turn. I actually machine stitch these onto the quilt using matching or invisible thread and the blind hem stitch
I do have the templates from the Eliza's back porch and love them but they are quarter circles and I don't think I would use them for whole circles.