I own the 15-85. It is a great lens. I do not have any direct experience with the 18-200, but based on the reviews I've read, I recommend upgrading your general purpose lens to the 15-85. You have the longer lengths covered with the 55-250 mm which is similar to better optical quality in comparison to the 18-200. So the 15-85 would be a good step up in optical quality over your current kit and still covers a very useful range.You would then have 15-250 mm covered with the two lenses.


I regard the 15-85 and the 17-55 f/2.8 as optically the best EFS lenses. The 17-55 has a significant advantage in aperture and the 15-85 has an advantage in focal length range. I think either would be a great general purpose lens for your kit.