advice on off brand wide angle alternative to canon 17-40 wth canon 6D

thanks for the advice on the tokina as well. I actually now remember looking at this lens as an option and it seemed like a great lens and a perfect fit for the price. As mentioned here again, I was actually thinking again that this lens may be the one that I want....but the fact that it does not hold filters is a big deal as I love using filters in my landscape and also I remembered it being quite heavy and bulky. Great solid build and feel, but for a non essential lens I felt that I need something much more compact and lighter for the backpacking kit.

It's amazing how small and light the 16-35 2.8L is...but on my full frame it just has so much distortion and it's so much more pricey.

I love to hear the great comments on the 17-40 though! Makes me feel a lot better and that I have made the right purchase!