Just to be clear - you mentioned going 'wide' but all the discussion is about 'ultrawide' - I'll assume you mean ultrawide for this thread.
All of these are pretty decent lenses and capable, but require a bit of a learning curve to know how to get good results. It isn't so much the lens that's the issue, but the style of shooting that a UWA lens requires. All of them will fare best when stopped down a bit, and all are capable of massive depth of field. All will have more exxagerated curvatures at the corners, all will be slightly softer in the corners wide open, and all will be slightly prone to some chromic abberation at the corners when at the widest angle. Knowing the right aperture and setting for your shot can help you get wonderful results from any of them. The faster lenses, like the Tokina F2.8 and Tamron F3.5, do allow you to use them in slightly lower light conditions handheld when you need to, but both will be even better when you get a tripod at night and stop them down a bit.
I've had a great time in the past 2 years with my Tamron 10-24 lens. I keep a lens/gear gallery online, so feel free to look through my gallery of all shots I've taken with this lens:
http://www.pbase.com/zackiedawg/tamron_1024mm_f3545_lens&page=all