A few points to consider vis-a-vis Nikon vs. Canon.
Nikon has been slow to update some of their lens lineup perhaps because they're leaning on the backward compatibility factor.
The higher end Nikon bodies (D7000 included) have focus motors so they can use older AF and AF-D (non AF-S) lenses.
The nice thing about the backward compatibility though is you can use old F-mount, manual focus lenses on your modern Nikon DSLR.
I have a 55mm f/2.8 micro-Nikkor manual focus lens described as "hellaciously sharp" and "the sharpness all other lenses are compared to."
I also have a Tokina 17mm f/3.5 manual focus that's awesome. It's my go-to ultrawide on FX (full-frame).
Finally, Nikon DX sensors are 1.5x crop making conversion easy. 50mm on a DX Nikon behaves like a 75mm on a 35mm camera.
My understanding of Canon crop sensors is they're something oddball like 1.6 or 1.65x.
Ultimately though, the reason I went Nikon after having Canons in the past: I find the Nikon user interface way faster to use and buttons more sensibly placed.