I am always surprised that here the focus is only on having as little credit cost as possible. Before that, you paid rent (interest) for years. You should rather think about how much money you want to have available in the next 15-20 years (besides the house payments), whether you also want to take a winter vacation now and then, buy new furniture/a car, or treat yourself to an expensive vacation! What good is it to you if you saved interest for 15 years but had to hold yourself together and make compromises for 15 years? For me personally, it would be no question at all, I would have taken 20 years and enjoyed life AND the house....
The current interest rate level corresponds, in my opinion, to the market-typical rental costs, and if this should still be market-typical after 15 years, I would constantly invest these 0.1% in value-maintaining measures. Incidentally, it has been statistically established that we live in a habitat that is indebted with more than 100 habitats, and no one knows how this damage will be remedied for our descendants.