Same as you. I decided to buy 17-55mm f2.8 and suddenly heard a lot of good comments about 15-85mm f3.5/5.6. Personally, I don't have any concern about the range (I know 15-85mm is better range), price (17-55mm is more expensive) and aperture. My only concern is the photos quality. Some users in other forum recommend to buy 17-55mm f2.8 based on the following reasons:
1. In 55MM, The aperture in 17-55mm is 3 stops bigger than 15-85mm. As a result, the bokeh is better;
2. Normally, the lower the range, the better the photos quality. 85/15 = 5.67 times and 55/17 = 3.24 times.
Most likely I will buy the 17-55mm f2.8.