Wow - This will be a difficult decision.
Their specifications are almost identical.
One thing really stands out for the Casio.
It has manual controls for:
....Who said you couldn't put manual controls in a tiny camera?
When I compare photos taken of the same subject, the Canon produces the sharper photo.
That does not say the Casio photo is bad...because it isn't. It is just that when you look at similar photos at full size I can see a slight difference.
At full size I am comparing minute details.
At less than full size, I can see no difference.
The Casio has the larger LCD screen 2.5 inches compared to 2.0 for the Canon.
The Canon has the stronger flash.
16.4 feet compared to 9.5 feet for the Casio.
The Casio has the least amount of shutter lag.
0.1 second compared to 0.5 second for the Canon.
I am glad you have to make the decision instead of me.
As far as the Powershot A90 - I guess you mean A95 because Canon never made an A90.
The A95 has the lowest price of the three.
It has manual controls.
It is a bit larger that the other two.
The photo sharpness is just about the same as the Casio Z750.
The Z750 photo shows more detail than the A95 due to having more megapixels.
Let us know what you choose.
I have been trying to decide on a camera for sometime now and have just about narrowed it down to either the SD500 or the Casio Z750. Does anyone have any reccommendations about these or other cameras I should be looking at(maybe the Powershot A90). Im having a hard time making a final decision and would appreciate some help.