Sigma 10-20mm, Tamron 10-24mm or tokina 12-24mm? Nikon D5100?

Can't afford a Nikkor, and if i go for the tokina, which is fixed aperture, I'll have to buy the non autofocus model, on a tight budget. Need it for wide angle scenery and architecture, including long exposures and HDRs, Since i will be in Jordan for a month, and my primary lens, a 70-300 VR2 is pretty much useless there. I need an answer in terms of image quality mostly, since my experiences with a Tamron and a Sigma have given me soft foregrounds, but maybe because they were non AF macro lenses. The Tamron seems better than the Sigma, since its f/3.5-4.5 on 10-24mm, and the sigma is f/4-5.6 on lesser focal length, but the sigma is slightly more expensive, which made me wonder about the tamrons quality. They both have inbuilt AF monitors, which I pretty much need. Feel free to suggest another lens in the same price range if you know of any.

After long long consideration I ruled out the Canon 10-22 on cost and the Tamron on quality. That narrowed my choice down to 3 UWA zooms:

The Sigma 10-20 f/3.5, Sigma 10-20 F/4-5.6 and the Tokina 11-16. F/2.8

The Tokina has a narrow zoom range but the fixed 2.8 max aperture would be great for interiors.

The Sigmas get mixed reviews generally being considered 1 star or 5 star. The 1 stars mostly relate to focusing problems; the 5 stars can't understand the 1 stars and love it. I know 2 people with this lens both had to return them to get a replacement but are very happy with the replacement.

In the end price won! The cheapest of the bunch is the Sigma 10-20 F/4-5.6. I took the risk on getting a bad one and having to return it. Didn't need to! What a fantastic piece of kit! Had it a week now and it is permanently fixed to my Canon 450D except for a small experiment when I fitted it to my film EOS and used it as a fisheye (heavily vignetted below 14mm).

It is giving pin sharp images across the whole frame - soft edges sharpen up at F5.6 and above. Build quality is superb - really smooth zoom and manual focus both with just enough resistance.

Guess what my recommendation is?

Independent reviews here (Canon site so no Nikons but the Sigma, Tamron and Tokina are all covered in comparative reviews.

http://www.the-digital-picture.com/Reviews/

Tokina recently announced a new Nikon version 11-16mm f2.8 with an internal focus motor that will focus on your D5100. Tokina calls their AF-S type lenses DX2.

So it would probably be called a Tokina "AT-X 116 PRO DX II" ( as opposed to the current "Tokina AT-X 116 PRO DX" ).

I have not seen that they are available yet though, or what the release date will be.

Non-AF Tokina or it just won't AF with your camera? Glasswise, Tokina is the best among the three. If you already have the 18-55mm kit lens then that should be more enough for your trip.

My vote is with sigma