What are you shooting? If you are doing landscapes and stop down to f/8-f/16 the 17-40 will give similar results to the 16-35. If you are shooting at f/4 you will get more quality by paying twice as much for the 16-35.
I don't know the Tokina but expect it is a "crop camera only" lens like Canon's EF-S lenses. You can't adapt it to a FF body without it cropping the corners on the image.
EOS: 7D (2, 1 gripped), 50D gripped, 580EX II + CP-E4
EF: 500 f/4L IS, 100-400 L IS, 70-200 f/4L IS, 28-135 IS, 1.4x TC II, EF-S: 15-85 IS, 10-22
5D3, 17-40 L, 24-105 L, 24mm TS-E II. S100 p&s