I love my Tokina 11-16. Unfortunately, it plunged onto a ravaging river in the midst of the Zion canyon. We have the same set-up. I will get another one as I am still lamenting on this lost.
I rented the Nikon 12-24. Definitely a fabulous lens for a DX body. Can't imagine using it on the full frame. haha. Haven't tried the others but I think for the price, I'd go for the Tokina.
I have it here and it's great for the price. VERY comparable to the 10mm Nikkor (if you look around for reviews/comparisons ) you'll see that favorable tests have come out on this unit.
The Tokina 11-16 f2.8 is an optical gem and built like a tank. I have been shooting since 1974 and until I purchased the Tokina I had been shooting nothing but Nikkors since 1984. This Tokina 11-16 f2.8 is as sharp and as well-built as any Nikkor I have owned and I have owned a small bunch of them . This includes 6 300 mm Nikkors (including 3 300 2.8's), several Micro Nikkors, a few zooms and a 24 2.8 Nikkor. The sharpest Nikkor I have owned was the 55 mm Micro Nikkor 2.8 AiS. This Tokina 11-16 f2.8 may be as sharp as that 55mm Micro Nikkor I owned.....I'm not quite sure. But I am sure that it is sharper than all the other Nikkors I have owned. Simply said.........I love this Tokina 11-16 2.8! I think you will love it too. Just check the rating it has on Amazon. All 5 stars. That might be enough for you to pull the trigger. It was for me.
I can't compare the Tokina 11-16 f/2.8 to anything, because it's really the only Nikon ultra-wide angle I've used. However, the reason I am jumping in, is that I rented it. I don't use super wides much, and I really couldn't afford to buy. But I could rent for the week I needed it. (I bought a wide angle for a different camera system once, and used it like five times, despite the fact it was my most expensive lens, so I wasn't in any hurry to actually purchase another. However, I needed it for a Yosemite trip.)
Anyhow, I was thinking this: perhaps you could rent a couple of likely suspects and see which one you like. I think the Tokina rental price is pretty cheap.
Are you sure about the photozone rating? I don't even see it. Their canon version -- what I have - is rated quite highly and I love it. I researched crop sensor wide angles quite a bit a few years back and the tokina was (and is) right at or near the top of the list.
I'd consider the 8-16 if you didn't need the speed and really craved what 8mm gives you. Supposed to be quite sharp too.
I also would vote for giving the Nikon 10-24 another look. I have the Nikon 12-24 and it's great. The 10-24 performs nearly identically, except it has an extra 2mm on the end.
Of the choices above, the Sigma 8-16 is unique in that it's the widest lens, and worth consideration for that.
The Sigma 10-20 is outclassed by similar alternatives (Nikon 10-24, etc.)
The 14-24 is great for sure, but at "only" 14 on the wide end, might be an issue for DX shooting
The Tamron 10-24 I don't know much about, but again most consider the Nikon 10-24 as the best performer for this "type" of lens (10-24 or 12-24 type range, "slow aperture" designs).
. This includes 6 300 mm Nikkors (including 3 300 2.8's), several Micro Nikkors, a few zooms and a 24 2.8 Nikkor. The sharpest Nikkor I have owned was the 55 mm Micro Nikkor 2.8 AiS. This Tokina 11-16 f2.8 may be as sharp as that 55mm Micro Nikkor I owned.....I'm not quite sure. But I am sure that it is sharper than all the other Nikkors I have owned. Simply said.........I love this Tokina 11-16 2.8! I think you will love it too. Just check the rating it has on Amazon. All 5 stars. That might be enough for you to pull the trigger. It was for me. 
(I bought a wide angle for a different camera system once, and used it like five times, despite the fact it was my most expensive lens, so I wasn't in any hurry to actually purchase another. However, I needed it for a Yosemite trip.)