The next decision is the frame material to select. The primary materials are wood, aluminum, fiberglass and vinyl. For the greatest strength and durability and security, choose fiberglass or aluminum. For the lowest maintenance, choose fiberglass or vinyl windows. If your budget is tight, locally-made vinyl or aluminum is a good choice.
Wood does require maintenance, but it is often the most attractive.
For the lowest utility bills, you cannot beat insulated vinyl or fiberglass frames. The glass is the heart of any window. Soft coat, also called sputter-coat, is more efficient than hard coat, but it sometimes is slightly more expensive. Beyond basic low-e, there are many glass options with benefits that depend on your climate. Ask to make sure that your window contractor installs them properly in your home.