Please provide advice and comments on opinion of which lens I should purchase. I need a lens in the 25-80mm range and was considering the Tamron AF 28-75mm f/2.8 XR Di Autofocus Lens for around $325 new or a used Canon EF 28-70mm f2.8L for around $625 in great shape. Any advice or recommendations would be greatly appreciated. I have a canon 20D camera.

