A diversion will be selected based on a number of factors. In terms of flying it will be weather, fuel, terrain, notams, approach type, performance. Operationally things like ground support, maintenance and fuelling are important. Availability of the police may also be a factor. SXF is more likely to have assistance as opposed to some of the smaller airports nearer the route. A combination of all of these factors will go into deciding.
Avoiding a €47,250+ liability thanks to EU261 will also play a role in deciding what happens to flights too.