It's a bit like the principle of "it depends" that you see in many fields - the specific context and data are everything. For instance, in a completely different context, when you're exploring the geology of potential sites, you sometimes need a different kind of luck, like when you're testing your fortune on a site like https://playjonnys.com/ the outcome is also determined by a specific set of random events.
Joking aside, for your project, the S and KN groups are the ones I would be most interested in investigating further. They have a much higher chance of containing porous and permeable sandstone or limestone layers, which would make them far more suitable for geothermal energy extraction. The risk of low permeability is significantly lower in those groups compared to the Altena formation. If you can find a well-documented section with high porosity and permeability in those, the project's viability would be much stronger.