[aarongzmn]

Since you are on this forum, I would guess your talking about pictures on your Touch Pro 2. Im no expert but I would say .jpg, is there another option anyway? I say jpg because its a compression format, meaning that the pictures aren't huge sizes and wont fill up your memory card so fast.

If your talking about a crazy high end digital camera, I guess RAW so that you can edit it easier in PS. Also, Way higher quality than .jpg.

If your talking web, then you want to go with the smallest file size possible without messing up the image quality too much. The most common for web are jpg, gif, and png (because it supports "seethrough" parts of the picture).

Again, im no expert but thats my opinion.