I use the machine quilting rulers. I have accumulated quite a few of them. I tried the free motion quilting, but I liked being able to have the 'same' on every quilt block and with the free motion that was hard to duplicate, for me anyhow. Especially since I do the QAYG method.
That said, I've seen a lot of beautiful free motion, but my hands just can't do it. I prefer the quilting rulers. A lot of different ones out there that make so many designs.