Go for the 15-85mm if you're sure you'll not go FF. It's a great lens - from an IQ perspective most copies of the 15-85mm are very sharp, produce contrasty / well coloured images. You won't notice an IQ deficiency when using the 15-85mm in comparison with the 17-40.
The 15-85mm has a wider zoom range than the 17-40. I'd find the 40mm tele end quite limiting. Also, the 2mm on the wide end are very useful. The 15-85mm has IS, whereas the 17-40mm doesn't. Both have USM / FTM. I use the 15-85mm on my 7D as my main lens, and yes, I have and use L lenses, but the 15-85mm is up there in image quality with many L zooms.
The main thing the 17-40mm has for it, is a slightly superior build quality (and of course, FF compatibiility). The 17-40L is constant aperture, but to me (and many users) that's not a big issue, especially as at 40mm the 15-85mm has just gone from f4.5 to f5.0 (which isn't much 'slower' than f4). So for me it's a no brainer.
All the best.