Which camera is better and has the widest range of features? canon powershot SD790 or SD880?

In my opinion, the SD880 is better than the SD790 since you get more optical zoom (4x vs 3x).

Both SD cameras are considered as point-and-shoot cameras. If you want wider range of features, you might wanna consider the SLR-like cameras. They sit between the point-and-shoot and the DSLR.

From your price range, the SLR-like Canon PowerShot SX110 would be a good fit. It's price is about $235, and it has a manual mode which allows you to adjust your own shutter speed, aperture value, ISO sensitivity, etc. (The Lumix DMC-TZ5A is a good camera as well, but I don't think it can operate in a manual mode). One down point of the SX110 is it doesn't come with a viewfinder so you can take pictures by just seeing through the LCD alone.

from these i prefer Panasonic Lumix DMC-TZ5A 9.1MP Digital Camera with 10x Wide Angle MEGA Optical Image Stabilized Zoom (Blue)

http://www.amazon.com/gp/product/B0011Z6D9U?ie=UTF...

Between the 2 I would go with canon S880.It is newer model with better zoom and DIGIC 4 Image Processor

http://www.amazon.com/gp/product/B001G5ZTN6?ie=UTF...

or another good one that I would recommend is Canon SD890 10MP with 5x Optical Image Stabilized Zoom.Good image quality, shutter speed, amazing zoom, fast power on, lots of advanced features

http://www.amazon.com/gp/product/B0015DPJMK?ie=UTF...

and another good one with great zoom Canon Powershot SX110IS 9MP with 10x Optical Image Stabilized Zoom.the CCD sensor is 1/2.3 inch which is bigger than the most SD series cameras resulting in better pictures.Sharp pictures - Daylight pictures are excellent and zoom is great for capturing landscapes

http://www.amazon.com/gp/product/B001EQ4C8U?ie=UTF...