Those often used are the Canon EF-S 10-22 and the Sigma 10-20. Your choices do depend on price though, so you'd be better adding a budget into the mix as well.
These are the best wide angle for cropped sensor cameras..Another vote for the Canon EF-S 10-22. Pricey but well worth it IMO.

I use a 17-55 and find that goes pretty wide on my 450D.
Those often used are the Canon EF-S 10-22 and the Sigma 10-20. Your choices do depend on price though, so you'd be better adding a budget into the mix as well.
These are the best wide angle for cropped sensor cameras..