I use canon's 17-40 , 24 F1.4 and siggy12-24mm on a FF body.
Probably the most useful is the canon 17-40, the 12-24mm is great, dead sharp, but at 12mm you can see behind yourself, so it's use is limited, but can be devastatingly effective in the right place.
If I was to pick one out of the three it would be the 17-40, although the 24mm F1.4 is a better lens.