This is a really tough question to answer as choosing a shoulder rest is all about player preference. I can tell you that Kun shoulder rests are the most popular on the market, and I have used them for about half of my career. There is nothing wrong with Everest shoulder rests, and I do have students currently using them. As a teacher, here are the things I would be looking for when it comes to holding your violin, which a shoulder rest should help out with:
1. Being able to fully support the violin with your chin and shoulder.
2. Have comfort to never grab the violin with more pressure in the hand when you shift.
3. Ability to keep the violin parallel to the ground at all times.
Technically, you can achieve all the points above without a shoulder rest, but most people find that they can help with the points above. You might not have known this, but some violin teachers fully support not using a shoulder rest at all. What they would all agree on though, are the points I highlighted above. Not using a shoulder rest in my opinion promotes holding the violin improperly as the violin can be uncomfortable when pushed up against your collarbone.