The nikon version. I'm pretty convinced that Canon (L) lenses are built better and tighter than any of the Nikon AF-S lenses
Any of them? There is nothing wrong with the build quality of the Nikon super teles, IMO. Nothing whatsoever.
But, IMO, the previous generation of AF-S pro lenses were better in that respect than the current ones (28-70 f/2.8 vs. the 24-70, and even the 70-200 VR II vs. the VR I)
The new 24 f/1.4 also leaves something to be desired as far as build quality goes.... considering it's a pro lens.
I'm sure the equivalent Canon lenses are built better.