Nikon has improved on their in-camera jpegs considerably since the days of the Fuji S5. I don't know if you would call their current results "comparable", but they are not bad. I was a long time S2 user, and was quite impressed with the newer sensors in the Nikon line due to increased dynamic range and higher ISO capabilities.
I first bought the Nikon D5100 for it's articulated viewer, and was very favorably impressed with the IQ. (It was also surprisingly compact and light in weight, but you may not like the menu system system for some settings) Then I got the D800E, for my fine art copy work, and landscape photography. Very fine camera with equally impressive IQ.
I recently saw they were selling D5100 kits in the $500 range. The kit 18-55 lens is actual quite good, and has VR built in. The newer D5200 kit is selling in the $900 range.
Hope this helps.