You will be pleased with any of the three.
I would pick the Canon SX260 because it only has 12MP, which will give you photos with less noise.
The other cameras has 16MP sensors which are too many pixels for such a small size sensor.
The camera makers have to use noise reduction firmware which will also remove the smaller detail.
The Canon SX500 uses older technology (CCD sensor instead of CMOS sensor.
CMOS is much faster when shooting in burst (repeat) modes.