Oh my...
This is a pretty big question lol.
There are many factors involved including the camera, lens, etc.
I would say that the biggest swing factor is the glass by far.
Good glass on a cheap body will look better than cheap glass on a good body as a general rule.
Pro level glass provides superior contrast/color/sharpness.
Most modern DSLR sensors are descent with good glass in front of them.
Larger sensors (FF for example) have better dynamic range and high Iso performance though, and they are ideal if you can afford them.
The cameras ability to accurately set white balance plays a big part in the quality of the JPEG that it spits out, this is not much of a factor if you are shooting RAW though.
Hope this helps.
- Neil