Either brand oil would more than do the job. Use whatever is more common and easier to find there. Since you are in Europe, Motul would probably be all over the place. For me, Mobil 1 can be bought at any store to top off if need be, that's why I use it. When it comes to viscosity it depends on where you live. If you are in an area where the temperatures don't get above 33*C for extended periods, just use the 0W40. If for example you have hot summers with extended periods of hot temperatures, then you can switch between the two. Remember, though, that the first number is for cold/winter viscosity - the "W" stands for winter. Since you're using 40 I assume your car is at least a few years old?
Since I live in southern California, I use 10W30 Mobil 1 and will continue to until I hit about 60,000 miles.
Switzerland huh? Must be nice over there!