I think it depends a bit on your prerequisites. Do you have some knowledge of craftsmanship, are you even professionals, or are you completely inexperienced? Are you building with an independent expert who advises you, or without one?
We based our decision completely on reputation. We know several people who built with the construction company and are still very satisfied after years. I looked at many online construction blogs, reviews on the internet, experience reports.
I also looked closely at the photos in the blogs – even as a layperson, I think you can already recognize some things if they look shoddy.
When building a house, quality definitely comes before price for me. Because you want it to last many years, not just until next summer.
Read through construction service descriptions, completely, and preferably before you go to the first appointments. Have them sent to you beforehand. I spent several evenings in the bathtub reading construction service descriptions.
After we had preselected the construction company, we also had them advise us on site and had a good gut feeling. I think that is part of it too. In the end, we didn’t choose the cheapest company (I’m not exactly sure where their prices are categorized), but we knew that they do many trades themselves. Where they work with subcontractors, they work in long-term cooperation with the partners. They don’t choose the cheapest subs either.
That gave me a good gut feeling from the start.
The cheapest providers also often work with the cheapest subcontractors; there is always a certain risk of bankruptcy involved, and we didn’t have the energy for that stress and risk.