Rugged, solid and precise construction. Focusing takes practice, of course, but there's enough room on the side of the lens to mark the infinity position for wide-angle and telephoto lenses, which could be analyzed closely in a controlled situation. So it costs money.
Canon EOS SLR Camera Lens EF 24-105mm f/4 L IS USM
124 Review
Nikon 35mm f/1.8G Auto Focus Lens for Nikon DSLR Cameras - Black (Model 2183)
125 Review
Black Canon EF 24-105mm f/4L IS II USM Lens - Model 1380C002
78 Review
New Nikon 18-105mm Vibration Reduction π· Zoom Lens with Auto Focus for Nikon DSLRs
104 Review