hi , I am a dual system user and my main camera is currently D800E.
I 'd say do not get the Nikon 14-24 , which is really overrated , it is not that amazing.
I mean it is sharp but has terrible distortion , terrible back light performance , does not take any filter , it is huge and heavy and difficult to take care of.
so I think you might want to consider the Zeiss 18mm f3.5 or Zeiss 21mm f2.8 or Nikon 16-35f4VR.
I use the Nikon 16-35f4VR on my 5DMK2.
The 16-35f4VR is a very very practical zoom , it's got great range with VR and it is quite sharp from 16 to 32mm range and it seldom flares.
I have the Zeiss 18 and Canon 24mm TSE for my 5D2 and I have been very happy with the TSE24 and I am considering replacing my Zeiss 18mm f3.5 with the Canon 17mmf4 TSE.
Anyway, I think most of people worship about the Nikon 14-24mmf2.8GED are not owners of it , they are just reading reviews and rave about it, it is a good lens optically , no doubt about it but it is also a very tough lens to use and extremely difficult to take great care of.