I have an original Grace Machine Frame which is wooden and will only hold a 9" throat machine. It was given to me. I was told by someone several years ago that the best made frame at the time was the Hinterberg Stretch. When I was looking at frames I also liked the looks of the Super Pro Flex. I agree with Alleyoop1, make sure your frame will fit a larger machine if you think you might upgrade later. I can't complain because the frame was free, but since I need to buy a machine to fit on it I would have liked the option of getting a larger throat machine. Good luck on your search.
Suzy