IMHO I find both feet invaluable. I use a walking foot when attaching a binding strip because it moves over bulk evenly, pressing from the top and bottom at the same time. I also use it for stitch in the ditch. I have used it with home dec and thicker fabrics too when piecing. The darning foot (or stippling foot) is great for machine quilting. Make SURE you have one with a spring-see picture-not a stationary or solid one. The spring moves with the up and down of the machine, keeping even pressure while you free motion quilt. The clear one (no spring) floats on the surface..bad. I used to have a Kenmore, and I was able to find both feet at a sewing machine supply place locally. They had universal feet. You will need your machine maker and model so they know if it is high or low shank and if it will fit-not all will. Call around to ask. FYI walking foot can run $45 to $75 and free motion with spring around $25 to $35.
No spring, no good IMHO
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Stipple Foot with Spring-good (Viking Foot Shown)
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