Can someone please help me......i am considering of buying one of these lenses.....can you advise me which is the best option for me?

Well it kind of depends on what you're shooting with and what you're looking for. I went with the Sigma 12-24 because I use a Canon 10D and I love wide angle. I had been looking at Canon's 17-40L, but that would have given me a 27.2 equiv field of view on the wide end, and I really wanted wider than that.

I haven't used either of the 17-35's, but from the specs their advantages are that they're faster (2.8-4 as opposed to the 4.5-5.6 of the 12-24) and the DX version of the Sigma 17-35 and the Tamron accept standard filters - the 12-24 has a built-in petal hood and only takes rear drop-in gelatin filters.

Here (http://forums.photographyreview.com/showthread.php?t=2341) are some examples from the 12-24.

Danielle