Oren....can't tell which lens is better, I can only tell you of my personal experience w/the 17-85IS.


I've shot this lens in a gymnasium at volleyball match....not my first choice because of the f stop, but I couldn't get my hands on a faster lens. I was pleasantly surprised w/the outcome....most of the pics were taken at 85mm and ISO 1600, a few a 3200 (not worth it) at shutter speeds that would blur the action (ball and arm movement) and maintain focus on the player and at other times stop the action completely. PP did include some noise reduction.


I also use this lens inside at family gatherings (that include a 3 and 5yr old) w/out a flash at lower ISOs....again pleasantly surprised and satisfied w/my results. I used 17mm for the family portrait (on a tripod...excellent result) and was zooming the rest of time w/quite a few 85mm shots.


I was not disappointed w/the results in sharpness, contrast, etc. Not all the photos were keepers, I would say about 25% were duds, but that's my M.O. []


Yes, I did need to perform some PP (to remove aberrations and enhance), i.e. cropping, enlargement, contrast, saturation, etc., but that's also me, I enjoy the PP of my photos.


Well that's just some of my experiences w/the 17-85IS....I'm satisfied w/it's performance and also enjoy my landscape results on my 40D.


Sounds like you'll enjoy (reading the Tamron owners points) whichever lens you chose.


Bill