While all shapes and forms of windows are available in both materials, vinyl windows have the unique ability to be formed into realistic wood patterns. Aluminum frames can be coated, but this 2D treatment can look unrealistic and fades over time. 

Since vinyl is plastic and not metal, it cannot dent and doesnt corrode when exposed to the elements. As pro #1 mentioned, the colour in vinyl is built-in and is very unlikely to fade over time. 

Vinyl windows require no maintance, unless they were installed incorrectly. To be sure no maintance is needed, have a professional install your windows. Aluminum frames require cleaning with a special solvent to prevent rust and condensation. Additionally, aluminium's coating will wear off and require repainting. Vinyl frames will never require re-painting. 

Metal conducts heat better than plastic. For electronics this is a great thing. But for energy-efficient windows, it is not. Vinyl frames do not heat up or cool down nearly as much as aluminum frames do. If you need maxiumum energy-efficiency our Energy-Star certified windows can lower your energy bill by up to 12%!

Overall vinyl windows will cost you less than aluminum. This is due to the simple fact that plastic is cheaper than metal. Considering the energy-efficiency of vinyl, the windows will pay for themselves in your energy bill!

For the average to larger size residential window, vinyl is perfectly strong enough. It is only for  extremely large commerical windows where aluminum should be considered. The only time that aluminum frames are used in residential builds are in hurricane-prone places, which Ontario is not!