My two cents worth: The one you keep depends on what you are sewing. If you are sewing multiple layers of thick fabric that are hard to get under your 403's or 201's presser foot, you will find the Kenmore has significantly more presser foot room and its 1+ amp motor plows through with little effort where the 403 may strain a little.
I have a number of Kenmores from that era that have built-in "stretch" stitches which make for nice sewing of knit fabrics if you have a need for that. Some like yours have a cam (either built-in or insertable) for a handy overcast stitch for finishing garment seams. The Singer also has a plastic cam (available on ebay) that will overcast seam edges more elegantly than a plain zz if your collection of cams do not already include this particular one. I also have a 403 with a complete set of cams that I like to sew granddaughter dresses with, You have a tough decision easily resoved by keeping both of them!