I currently own a Canon 5D classic and have no intentions of selling it(I don't think I ever will, I absolutely love it). I am also covered from 24mm onwards. I have also owned multiple copies of Canon 17-40/4L over the years and it is a terrific value for what it brings to the table at that price. But I have always felt the need for better.
With that background, here are three interesting options that I am looking at:
1. Current Canon 5D Classic + a chipped Novoflex Nikon G to EOS Adapter + Nikon 14-24
2. A brand new Nikon D7000 (I happen to have one that I was looking to sell but can always keep ) + a Tokina 11-16/2.8 DX (Plus I will be keep my Canon 5D which I will be using for 24-xxx focal lengths)
3. Current Canon 5D Classic + Tokina 16-28/2.8
Which one would you chose and why?
P.S. I am a filters guy and use Singh-rays on the Cokin p-System. Though the N14-24 and T16-28 lenses don't accept screw in filters, I can get creative and build a DIY kit that takes the filters (although I might have to move up from the P mount to a larger sized one if the P size won't cover the entire glass area). So though an important factor into the decision, I can come up with workarounds for the other lenses which kinda evens it out on the filters front. So factor in the filter aspect only to the extent of additional effort it would take to build a filter mount.