Canon 18-135mm

[ROCKMORE]

Here are some charts comparing distortion in Canon wide zoom lenses.
The 10-22mm seems to win with the least distortion even at the 10mm mark which is far wider that any of the other lenses.
The 10-22mm at the 14mm mark appears very straight

I was unable to change the name of this thread

 

[ROCKMORE]

Here are the charts I found which may be helpful in selecting a wide lens with the least amount of distortion.

http://www.photozone.com/ If you want to read the complete test on the lenses.