What are the best SLR Cameras for low light and journalism?

I have a Canon xsi and I've had it for 3 years not. I love it but it's time for an upgrade. I run my own business and I recently got a gig with the local news paper shooting photography and I wanted to know what you guys think is the best camera (nikon or canon) that is great in low light. My budget is $1500.

Buying a new camera is pretty much the least efficient way of dealing with lacking low light capability.

What lenses do you currently own? Investing in better glass may be a far more efficient way. E. G.a lens that can open up to f/2.8 will let in four times as much light as one that has to work at f/5.6
A camera that offers such a boost in low light capability by having a better sensor will be more expensive than such a new better lens.

Keep in mind, if you go full frame, then you won't be able to use any EF-S lenses that you currently may own. You'll have to rebuy EF lenses. The need for such new lenses likely will put even the cheapest full frame cameras out of your budget figures, such as the Canon 6D or Nikon D600.

So… Investing in lenses, perhaps a monopod or a powerful flash will be your best options. In terms of cameras, there isn't really any difference in low light capability even between the T2i and 7D, or between the D5100 and D7000 on the Nikon side. All of these are better than an old XSi though, but don't expect wonders. A fast prime lens or fast zoom on the other hand will do wonders if you don't have any of these yet.

I don't see the point of switching cameras now. If you buy Nikon then you have to use your Canon for a back up camera. That's fine on the surface, but what if you decide you want a special lens for most of your journalistic photography and the camera shuts down? Then you have to use the Canon without that special lens that you prefer. When I was in journalism I liked an 80mm (35mm camera) lens for much of the work I did. But I could not and can't see purchasing another lens from a different manufacturer (Nikon) to be able to shoot both systems. No one in his right mind would recommend owning both systems (Canon and Nikon). Your question is WRONG. You should be asking what lens, and ISO combination is best for journalistic photography. And that depends on the sub-nature of your work. For Instance, I shot mostly for magazine use and was always shooting people, not sports, not ground breaking, but people in business, that's why the 85mm was the best lens for my primary use. Today with digital, you have to ascertain what specific lens will do: most" of your work and purchase the lens with fastest speed you can afford. I imagine that a 50mm f1.4 would do the trick. But then I have been out of this part of the business for many years.
Also you want to consider the largest possible enlargement that you will make in regards to your ISO setting. Your newspaper shoots for the most part will be relatively small is size, but you will probably want to make enlargements 8x10 or 11x14 for your portfolio. When you change jobs, a portfolio is the main part of your resume.

Some good ones at low-light is the canon t4i/650d or the nikon d5200. They both have decent pictures at iso 6400+.

I'm a big Nikon fan, but it depends a bit on what lenses you have as to what the best choice is.

Full frame cameras are best in low light, but $1500 would limit you to second hand. The full frame sensors are larger and that means bigger pixels, so you get more light per pixel, so less noise at high ISO. Do you already have full frame Canon lenses or are they only the smaller APS-C sized ones?

If you are sticking to APS-C/DX sized cameras, the Nikon D7000 is still the best low-light camera in the market in that price range. It's a solid workhorse. If you can stretch the budget a bit further go full frame.