All cameras like the SX40 HS are very close in quality; there is not one significantly better than another. This is because they all use a digital imaging sensor of approximately the same size, and they all use lenses that have approximately the same aperture range (the aperture is not the zoom). Some cameras will be faster, such as the Nikon P500 or P510, but the speed will not help in low light...you would still get blurry pictures.

So...all small inexpensive cameras will work well in good light, but none will work well in low light if they subject is moving. The best choice is to choose one, and if you need to use it in low light of moving subjects, shoot video instead.

If you want a smaller camera with a good zoom range that is fast, look at the Nikon S9100. It has what you want, except for working well in low light moving subjects. It can work pretty well in low light stationary subjects with its Night Landscape and Night Portrait modes.