Upload & Sell: Off
Meyson, I understand you're searching for a lens for your 60D. I think you should focus more on what range of focal lengths is suitable for your need, rather than the best pictures that someone else has taken. Both 24-105L and 17-55 IS, and even 15-85 IS, are all capable lenses and they're not that much apart in term of image quality. I believe, say, at 24mm, I can produce just about the same image from either lens.
That said, I find that the lens like 24-105L is not good on cropped. I even tried to use it when carrying two cropped bodies: one with 24-105L and one with 10-22. (I normally carry two bodies.) And I still find it didn't work for me mainly because it's not wide enough. Even 17-55 IS and 10-22 on two bodies didn't work for me because it doesn't have enough reach.
In the end, the solution that worked for me when I used two cropped bodies was 15-85 IS in one body and 35L or 24L II in another.
So, the bottom line is I think you should find the range that works for you.