What do you mean by best Aluminium Windows or how to find best window systems in market ?

Mr. Sumit suggests to check several points;

1. By checking the sections are extruded locally or by best extrusion companies in Europe etc., we can have fair idea of costing of the system.
2. Check aluminium composition whether it is 6063 T6 or less.
3. Best Aluminium Window system comes with thermal break sections for best insulation.
4. Best window system comes with European specifications for Air permeability, Wind Resistance, Water Tightness, U values, Energy coefficient etc..
5. Some companies in Europe provide extra ordinary finishes, like CORTIZO & Ponzio. Some are certified by (Qualicoat for powder coating ) or (Qualando for anodising).
6. Slimline Windows with only 20mm intersection give best aesthetics & whereas Lift and Slide Sliding give the most comfortable drive. These are the most  revolutionary technologies in Window systems.
7. Almost every company provides the technical literature of each system to check its maximum height possibility, & how much thick glass can be used.
8. Mesh is important when you are in country which has tropical weather conditions, so many system companies still don’t provide a dedicated same sash for mesh shutter.
9. Best & latest European Hardware’s can only be installed if the system section comes Euro Groove. 
10. By checking is company giving the Multi point locking ? & by checking Hardware opening & closing cycles also gives you the fair idea of quality of hardware being used in the system.