You can just flip a coin to decide between Canon and Nikon, they are very similar in quality.
For low light action shots, the lens is more important than the exact camera body used. If you want zoom lens, f/2.8 is the most you can get. But you can get wider aperture for less money with prime lenses. So it depends on your budget and preference. But lenses in this category can easily cost more than the camera body itself.
There are many ways to take low light still photos, using fast lens with IS, tripods with slow shutter speed, flash (regular or rear curtain), flash with intention motion of the camera to create background light streaks, etc. Choices are limited by your imagination, not the camera body.
For other shots, try to use as low an ISO as possible, and learn how to use external light if the ambient light is suboptimal or too dark. A better indoor portrait is accomplished with strobes and tripods, not necessarily with a faster lens (many people actually stop down to f/8, f/11, etc). For outdoor portrait with good ambient lighting, the 85mm f/1.8 is usually a good buy.
So just make a choice or flip a coin. Canon and Nikon are both very good, you won't regret your choice. Good luck!