The type of window you need is closely related to what you hope to achieve with your replacement project. Here are some pros and cons of various window types of some of the manufacturers that we work with.
COMPARISONS

Below is a "general" summary of the pros and cons of various window frame types. The ratings and opinions expressed are relative and arbitrary and should be used as discussion points when choosing between specific frame types.

Highest/Best
****		 Aluminum Vinyl Wood Fiberglass Composites
PRICE * ** **** **** ****
QUALITY * ** *** **** ****
U-VALUE * **** **** **** ****
WARRANTY *** **** ** *** ***
MAINTENANCE *** **** ** **** ***
COLOR * * **** ** ***
ALUMINUM FRAMES
PROS CONS
Least expensive
Narrowest Frame Profile
Special Colors Available
Minimal - No Maintenance		 Poorest Insulator
Warranties across the industry not as long as vinyl
Greater Susceptibility to pitting and corrosion
Most are Mechanically fastened corners

VINYL FRAMES

PROS CONS
Excellent Insulator
Frame Profiles more consistent with
   wood profiles
Fusion welded corners
No Maintenance
Long warranties		 Heavier Frame Profiles
Limited Colors - (Paintable New Technology)
Requires more experienced installers
WOOD FRAMES
PROS CONS
Excellent Insulator
Can duplicate existing wood
Unlimited choices in colors / stain
Beauty/Warmth		 Expensive
Limited Warranties
Continual Maintenance
Limited product offerings for replacement windows
 
FIBERGLASS FRAMES
PROS CONS
Excellent Insulator
Frame profiles more consistent with
    Wood profiles
Unlimited choices in colors / siding
Good Warranties
Strongest, most dimensionally stable
Environmentally correct		 Expensive
Not all are easily retrofitted
Must Maintain Interior Finishes (Woodclad)
Long Lead Times
Lack of Consumer Awareness
 
COMPOSITE FRAMES
PROS CONS
Excellent Insulator
Good Warranties
Frame profiles consistent with Wood		 Expensive