My favorite shoulder rest is the Everest. I like it because the feet are made of solid rubber. A lot of shoulder rest feet are plastic, covered with rubber tubing. When the tubing wears down, the plastic can damage your instrument. 🙁
The Everest is slightly adjustable, and I find that is all you need. You can make it wider/narrower, and adjust the height of the feet.
Suzanne from Violin Tutor Pro