Upload & Sell: Off
I never considered 35L or 35/2 on my 30D (now 7D) for low light because I thougt it would be to narrow. Never considered third party lenses. So for a couple of years I used Canon 28/1.8. It was my most used lens although I also owned the EF-S 17-55 IS. I liked it very much,very lightweight and versatile, highly underrated lens on the Internet and forums IMO. Usually used it between f2.0 and 2.8. Then I upgraded to a used 24/1.4 L (mkI) and sold the 28mm. I'm very satisfied with the upgrade due to sharpness, bokeh, color, but still miss 28/1.8 for the light weight (310g vs 550g). The 24/1.4 is now my most used lens together with 50/1.4, - it's a great combo.
I find the EF-S 17-55 gives excellent images and the IS is really helpful in many situations, but the weight (645g) and size (with hood) makes my prefer my primes. I also have 85/1.8 and 200/2.8, but rarely use them because of the focal length.
All in all, for 7D I would recommend either 28/1.8 or 24/1.4 if you can afford. (If you need 35 mm FL, just crop in Lightroom/photoshop/other software).