I'd stop looking at sharpness and note how much Bryan dumps on the Tamron's AF. The Tokina doesn't have the equivalent of USM either so IMO if the 2.8 aperture isn't vital one of the Canon lenses would be better. Here's why:


1. The tokina has the 2.8 aperture but doesn't have IS. Get the 70-200 f/4L IS and you'll still be able to take pictures in low(er) light.


2. If you're looking to use the tokina for sports, remember that its AF (and that of the Tamron) isn't as good as the Canon's.


3. I don't mean to say this in a radical way, but just avoid Sigma and Tamron. (yes, there are some exceptions) In my mind something that costs $1000 and then doesn't AF properly (a problem that Bryan has experienced with MANY of their lenses) is a waste.


If you aren't looking to shoot action and want the f/2.8 aperture, I'd pick the 50-135mm. For the added benefit of IS, weather sealing and fewer distortions, I suggest the 70-200mm f/4L IS.


my 2¢