7D + Canon 15-77 2.8IS vs D7000 + Nikon 15-77 2.8?

Pentax K5 + 16-50 2.8 sdm ?

I have actually tried all three cameras, I liked the 7d nice decisive autofocus, a larger well constructed camera.

The d7000 really doesn't seem up to the build quality of the pentax and canon and the autofocus seemed about the same as the pentax. It should be slightly better for tracking. I didn't like the feel though but this is a personal taste thing, you should really try the cameras out to see which you prefer.

If you are starting from scratch you might want to consider the k5, the 16-50 is very nice as well. in either case I have heard great things about the sigma 17-50 2.8 if weather sealing is not important to you. I am not trying to start a debate just offering up my opinion.

BTW I am sure they all take excellent pictures and you probably be happy with any of these choices.

Good luck