The Canon EF 20/2.8 isn't terribly wide on a 7D, but personally I think it's a very nice lens. This is on a 50D with B+W Kaesemann C-Pol filter...
On a crop camera, the 20/2.8 pretty closely emulates a 35mm lens on full frame. Maybe that's why I like it on both crop and full frame. I've always been a fan of 35-40mm on film/full frame.
I don't know why there are bad reviews. As far as I'm concerned it's a fine lens. I also like 20mm on full frame and find the EF 20/2.8 to be pretty well corrected (much better than some 20mm/21mm lenses I used in the past). These two shots are done using it on 5DII, both also with the C-Pol...
Maybe the reason the 20/2.8 gets panned is because it's about equal image quality to the 17-40/4L and 16-36/2.8L II, both of which give the convenience of zooms.
If you need a bigger aperture, there are the Sigma 20/1.8 and 24/1.8... I've heard/read a lot more problems with them (slow focus, softness in some areas of the image), than with the Canon 20mm. Both these Sigmas are also pretty hefty lenses (the Canon 20mm isn't small, but not as large or heavy as the Sigmas).
The Canon 24/2.8 is a very sharp, light, small lens. Relatively inexpensive, too... It doesn't have USM, though.
There are the new Canon EF 24/2.8 IS and 28/2.8 IS... Both of which are STM lenses, but they're pretty expensive. Approx. double the price, to get IS and better focus than a micro motor.
Canon EF 28/1.8 is a good, bigger aperture, quite compact, fast-focusing USM lens... but it's not very wide on a crop camera there's not much difference between it and the 35/1.4's focal length.
The 24/1.4L is fairly sizeable and heavy, not to mention quite expensive for a lens that's only slightly wide on a crop camera.
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