Each has its own advantages. Since you don't think grammar is a big problem, go to Goethe, where the language environment is better and the class size is smaller. All classes are taught in German, which greatly improves oral listening.

If you feel that the foundation is not very good, you can choose Rhine Spring first. The teachers there teach very well, but there are more students in the peak period, and the language environment is not as good as Goethe's, but the teaching quality is really high.