if you are looking for super wideness, then go for the sigma 8-16mm, super sharp across the frame but cannot use filter without specific adapter.

the canon 10-22 is good i think, has USM and good IQ.

sigma 10-20 in the other hand, has both 2 versions with different aperture. i tried one of them before (can't recall the exact model), the corners are quite unusable wide open but good enough after stopped down like f8 and beyond.

then there's tokina 11-16mm f2.8 for the big aperture.

there's no way you can put any filter on it because of the bulbous front element. unless you get some special adapters that will created a filter thread to hold filters.