Before I came to Switzerland, I wanted to pre-order two sim cards. I had questions then, and would like to give my experience for others now.
First, the Swiss companies, SwissCom, Sunrise, and Salt only work in Switzerland (I physically stopped in each of their shops to ask) and if you cross any surrounding borders, there are added fees. In addition, all are fairly expensive.
We bought Vodafone and Three UK from Amazon. I would not suggest Vodafone as their coverage breaks up often, and that is annoying. Three UK has been fabulous. They say you can't use it as a hotspot, but I have done it. Three UK has worked in Germany, Austria, Lichtenstein, Germany and Italy so far. Both plans cost around $35 with 25 GB of data for 30 days, more than anyone can reasonably use.