I'm with you there! The problem with the Nikkor 14-24mm lens is that there is a very vocal group who keep telling every one that it's the best wide lens ever....and yet filters are a pain. The curved front element is very prone to damage and even water drops seem to get magnified on it. Sure it's image corners are sharp wide open, but it's not a lot greater than mose wides when stopped down (ie landscapes). It flares badly due to the bulbous front element and the angular distortion is quite high at 14mm. I don't really see much photographic value of those extra 2mm over the far more versatile 16-35IIL.
The 16-35IIL is a little dated as a design. Newer coatings would be good and less CA. Sharpness, well it's OK but I'm sure Canon can coax a little more line resolution out of a re-design. The thing I love about the 16-35IIL is that it is so versatile. It does so much so well. If I need a wide lens I can rely on...its a 16-35IIL.
I had a 17-40L for a few years. It was very nice and almost the equal to the 16-35IIL optically, except the f4 and focal range. I really liked this lens but I needed the extra stop. I used to have an ef-s 10-22mm, which again was very simular. Not as bright but again very simular to the 16-35IIL. I'm sure the extra focal range will be welcome by many although not the revised entry price I'm guessing! I don't really see the need for an image stabiliser on a wide lens. Although a lot of people will be using this lens on a 1.6x crop...so I guess it makes a bridge lens for 1.6x to full frame migrators. on a 1.6x crop it's an effective 25-80mm, quite a nice range.
Given that all of Canon's recent lens releases have been steller (I think everything AFTER the 50mm f1.2L have been amazing optically), I'm sure these two new lenses will be remarkable.
I am sorry to disappoint you, but as a Canon user I must admit that yes the Nikon 14-24 is THE best ultra wide zoom, EVER!
It is not perfect, and yes it is prone to flares. But in most situations I can live with the flare, or the flare is not present.
I would take the flares, and the lack of shitty filters, on any given day, as long as the lens is optically superior you will find ways to work with all the other "flaws" !
If Canon is smart, they will allow for gelatin filters at the backend, like the 17-40. But hey, filters are so nostalgic, do multiple exposures and blend in post!!
Yes the 16-35 II is versatile, but it it does not do justice to my 7 grand 1DX or my 3 grand 5D3 !
Even the heavy moustache distortion, and the vignetting on the Samyang 14 is correctable in post!
The mushy corners and the insane CA and coma distortion in the EF 16-35 II (and the EF 14 2.8 L II), is impossible to correct in post!
But I would take both a 14-24 2.8 L and a new versatile improved 16-35 2.8 III !
Just BRING EM on this time! And don't let us wait in vain (and pain)!!