I think you need to consider several criteria and not just if they are considered to be rich stable. Also in terms of languages it is very important. You would need to have a good knowledge of the languages needed. If you like Norwegian or Finnish then you should listen to them and see if they are really what you want or German. It seems that the language you want to learn would be a good way to make your decision. You need to consider long-term what it is that you want to do and want to live/work. All these countries have positive and negative reasons, you need to weigh them up. Make a list. But, if you already have learned some English, it may be more sensible to pursue study at an English speaking university.

You should consider the comparative size of the countries in question. Germany is Europe's biggest country, while Norway and Finland are among the smallest, population-wise.