IMHO, I wld go for the D300s depending on your primary use of the DSLR.
How often do you do HD video vs still shoots?
Do you also need mega-pixels ie 16mp vs 12mp? Most often, 12mp is more than enough unless you wanna do huge prints. Either way, the D300s is sufficient.
Is fast AF important?
D300s has gained a respectable reputation as a DSLR; has quite a following and also used by pros...
D7K is relatively new and at the rate Nikon is churning out entry-level or mid-entry cams, I wont be surprised if D7000S/8000 is already in the pipeline.If you are one who's into newer models, by all means, get the D7000 but get a good lens to go with it. Good, I mean, a 17-55mm f2.8 lens. My humble 2-cents