All of the machines you mentioned are part of the list of classics. They are all wonderful machines in their own right and all a little different. I suppose it comes down to what you plan to do with it and how much space you have. If $ and space are no problem then collect one of each and play and enjoy your collection! If you want to actually quilt on it either the 201 or the 15-91 have a bigger harp and would probably handle FM quilting much better than a 301. The 301 is a great machine to stitch on but you will have to have the feet and attachments to fit it as it is a high shank slant needle machine and regular feet won't fit. Lots of decisions for you.