Upload & Sell: Off
Well, I can't imagine why you'd change who systems then get the 17-40 over the 16-35 f2.8 MkII. (with all due respect to those who have this lens). The 16-35mm MKII is the best wide angle Canon has produced and I've used them all.
Either that, or pick up an adapter and the 14-24 Nikkor for the landscapes. That's pretty much as good as it gets for me.