Both! Seriously, reading your profile, since you are Pro and shoot mainly Landscape I would see no need for a D4. I am not sure you need either
If your equipment profile is up-to-date then some glass new could be a consideration.
More information on why you feel you need one or the other would be helpful:)
Best of luck. You might want to post on the appropriate camera forums but since neither is really in any/many member's hands..... most will be looking at the specs. Tom
Edit: Armando types faster than I do I just had a look at October House. I only saw one action shot..the dog shaking itself.. so I stick with no D4. I can see where you might want better high iso for events, schools, weddings and you might want higher Res. and more MP if you want to print your landscapes really big. You might want to look at a D3/D700. If you really need a tax right-off ....