I was faced with this decision last month, and was drawn to the 2.8 because I shoot events as well as architecture professionally. My 17-35 is awesome on my d800 for both genres. Are the corners a little soft at 2.8? Yes. Who cares? Only brick wall shooters. If I'm shooting something that requires corner to corner in focus, I'm stopped down. If I'm shooting an event, people etc, I prefer subject isolation, where I want a sharp central portion of he frame. The 17-35 excels at this as well. So I get people sharp at 2.8 and everything sharp at f8. That's the way I shoot so this lens works for me.