In my opinion, the manufacturer is not decisive at first. For the builder, the requirements should be checked first, which type of window makes sense to be installed where. Considerations important to me would be, for example, the material used: Wood: + good thermal insulation, easy to work with - requires high maintenance Wood/Aluminum + good thermal insulation + low maintenance due to the aluminum cladding Aluminum + very robust, low maintenance + weather resistant + lightweight, which benefits the statics + non-combustible - production is very energy-intensive Plastic + low maintenance - more prone to dirt due to static charging - relatively large frame thickness just to name a few. Additionally: > lighting > ventilation > weather protection > sound insulation > thermal protection > fire protection > protection against burglary So you can see what can or should be done, and of course, this is reflected in the price. It can make sense to compare prices, but only if offers are explicitly requested with the same specifications. Nevertheless, the saying I recently heard from the window installer also applies: "Every window is only as good as it was installed."