Take a look at all the various DSLR options out there. Try them all out and see which one has the most features for the money and feels the best in your hands. If you're comparing in the same price points the image quality betweek a Sony, Nikkon, and Canon will be negligible. Especially between Sony and Nikkon as Sony makes the image sensors for all the Nikkon cameras. You will find that lens selection impacts image quality more then camera brand.
I would recommend getting something in the 12-16mp range. I shoot with a Sony a55 and am thrilled with it.
www.dpreview.com is full of camera reviews.