Which canon powershot elph digital camera is the best to purchase?

I agree with Petra. I own and love the SD900. I might be as happy with the new SD850-IS. It's a smaller sensor, but the "IS" is a valid feature that really helps.

I think the SD900 is still the tops. It has 10 MP and it's the only SD that has the larger 1/1.8" sensor, which is nearly twice as big as the sensor in any of the other SD cameras. This generally translates into better image quality with lower noise. It's the one that I bought as my own personal pocket camera.

Here are a couple of reviews for the SD900:
http://www.dpreview.com/reviews/canonsd9...
http://www.steves-digicams.com/2006_revi...
http://web1.popphoto.com/cameras/3468/te...

Be sure to note that the reviews are many pages long so you don't stop after page one. Check the sample images, also. You can enlarge these to full size images if you click on the link below the picture. You will have to then put your cursor in the white space to the right of the picture and click once. After that, you can pass your cursor over the image and it will turn into a magnifier. Click it as a magnifier once and the image will go to full size and you can really examine the detail or look for artifacts like fringing or noise.

Here is one photo I put on-line that I took with the SD900. Click on "All Sizes" and view this as large as possible and check out the birds. (They are NOT digital noise!) Look at the tips of the branches of the trees to evaluate sharpness. This was taken right after sunset and there were no enhancements in afterprocessing. http://www.flickr.com/photos/7189769@N04...

Here's another photo with no post-processing at all. It was taken at the full 111 mm (equiv) zoom. It was taken in the fully automatic mode with no help from me at all. The horizon is crooked because the camera was resting on the top of my car. I did not want to alter anything, because this is part of a 3-image series comparing optical zoom with cropping to digital zoom. You can look at the other pictures while you are there and see why optical zoom is all that matters.
http://www.flickr.com/photos/7189769@N04...

Compare the photos here BEFORE you read the whole description. Choose your preference and then read on to see which camera made which pictures. The SD700-IS has been replaced by the (better) SD850-IS.
http://www.flickr.com/photos/7189769@N04...

The latest models are the best choice.
The newly announced...
SD850 IS (Ixus 950 IS), 8MP, 4x optical image stabilization

or the SD1000 (Ixus 70), 7.1MP, 3x optical
or SD900 (Ixus 900 Ti), 10MP, 3x optical