What are the pros and cons of different double glazing materials?

Question

e.g., uPVC, hardwood, softwood, aluminium (anything else out there?), especially in terms of cost, looks, durability and maintenance needs.

Answer 1

uPVC is hideously ugly and discolours fast. Hardwood is class, but needs periodic wood treatment. Softwood looks good but rots very quickly unless you maintain well - which also means often. I didn't know aluminium window frames existed any more. They are as nasty as uPVC in my opinion and crumble.