Choice is so hard...

I like the build quality of 17-40, and especially its weather sealing (I live in Vancouver, so it rains quite a lot, plus I sometimes travel to Taiwan, which is quite humid). Don't have a problem with its IQ (though that may change once I get the 70-200). On the other hand, it's not like I shoot outdoors in the rain a lot, and I'm sure people in Taiwan also use non-L glass, too, and have no problems with hit.

What attracts me with the EF-S 17-55 is its low light performance & alleged IQ performance on a cropped body.

*Pulling my hair out*