Canon TS-E 24mm f/3.5L II

Pros: Sharpness, overall image quality, lack of CA, extended shifting capabilities, build quality, design (it's nice!), independent shift/tilt Cons: None. Well, it is not exactly cheap... After using the 24 TS-E I, which is still a good lens, the Mark II will amaze you. Kudos for Canon engineering! As others have said, this may be, with ease, the best wide angle lens ever built by any brand for 35mm photography...