If you choose D800 (E) then you need the best (most expensive) lenses.
The D800/E takes as good a picture with non optimal glass as any camera, in fact probably better. What it has is the potential to use the performance of the best lenses and show what they're capable of. That's a different thing altogether.
As for the DF I just don't get the price. It seems the biggest point people harp on about is using old lenses. When I bought my D800, at no point did I wish I could start shopping for glass in a charity shop. It's like paying twice the price for a car that can use dirty cheap fuel.
No video is a plus. Come on you can't score cameras down because Nikon didn't cripple a feature you don't use. It would cost more to remove it in most bodies. I don't shoot video very often, maybe a couple of time per year. However, I'm glad I can as I don't have a video camera and don't want the expense of one at that level of use.
If the DF was under £1000 I would consider it as a nice gadget to own which is a bit lighter to carry around and obviously has a great low light sensor. But, I think it looks a bit strange when you put modern AFS lenses on because they are much bulkier than the legacy glass.
Those things said, if people who have bought the DF are enjoying owning it, that makes it good value to them. I wouldn't want anyone to analyse my purchasing logic over recent years as it may be challenging to defend!!