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