FWIW, I own the Tokina 11-16mm f/2.8 and although I don't do a great deal of UWA shooting, I don't think that I could find a better UWA DX lens :shrug: - there's just nothing much* bad to say about it!
Build quality is superb, optics are dead sharp and free of overly complex distortion and it's a lot cheaper than the Nikon equivalents.
*I suppose that the biggest two (potential) negatives with it are;
a.) the fact that the zoom range is narrower than most (although generally, if I use a UWA lens, I generally favour the widest settings anyway) and
b.) the switch from Manual Focus to AF is made by pushing/pulling the barrel of the lens and mine has sometimes been pulled into MF mode whilst moving it in or out of the camera bag. As such, I think that I have AF'd on the right area and it's only when I see the detail on the PC that I realise I was in manual and focused on the wrong area

. This would be easier to spot on other lenses, but because of the very deep depth of field at the wider FLs and the tendency for there to be less large subjects in the frame (often), it is surprisingly easy to get it wrong of you are in a hurry. Personally, I'd prefer a normal switch for MF/AF selection :|.
Good luck with deciding

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