These two cameras are aimed at the same customer.
I suggest you pass on the SX500.
It uses the older CCD sensor assembly which means its burst speed drops to about 1 frame per second.
The other two cameras use CMOS sensors and their burst rates are up around 10 frames per second.
As far as Low Light, neither camera is above average in that category.
Their small sensors are the problem.
DSLR cameras are still what you need for low light.
Sony is using an 18MP sensor which means the individual sensors are much smaller than the Canon's 12MP sensor.
This means more noise and that requires noise reduction firmware in the camera. And that means loss of very fine detail. It will show up when you print pictures larger than 8 x 10.
If you like lots of features and gee-whiz things, Sony wins that race.