Canon EF 100mm f/2.8L Macro IS USM
There little doubt that, all round, this is one of the very finest lenses we've seen - optically it's superb, and operationally it works very well too, with fast and positive autofocus, and one of the most effective image stabilization systems currently available. Throw in the high build quality, including dust- and splash-proofing, and it all adds up to a very desirable package indeed.
This lens is superb, and optically, there no serious black marks against it. It offers exceptional image quality and refined handling.
Its Hybrid IS system is great for normal use, but is not terribly effective for close-up macro work.