I have not used the Tokina 11-16 before. But I have used both the Sigma 8-16 and the Canon 10-22mm. Of the two, I prefer the Canon. One reason is because I personally find the focal range more useful and I prefer to sacrifice the extra 2mm width for the 22mm reach (equivalent to about 35mm) which means I could still use it as a reasonable walkabout lens. I sold it after I upgraded to FF, but it was one of my favorites.
Btw, for group shots, you don't need a fast lens because you probably shouldn't be shooting at F2.8.