I went through the same process 2 years ago when I purchased a Canon 30D. I was considering between exactly the same 2 lenses and I went for the 24-105 since it has a better coverage and I don't like changing lens so this works better for me. Now I have upgraded to a 5D Mark II and I am using this lens with the full frame sensor has proven my decision was good.


If you are going to keep the XSi or in the future upgrading to a 50d, I would like to suggest you look at the EF-S 17-55mm f/2.8 IS USM. This is a good lens with a better wide angle coverage. Excellent for traveling and a walkaround lens. If I have extra money, I definitely will go for this lens for my 30D and use it for travel.