"The GIF format can have a maximum of 256 colors. GIF files support transparency and animation, and work best with graphics that have large areas of the same colour, JPEG format works best with photographic images or images that have more than 256 colours and gradients, images saved in JPEG format are compressed, which means that image information will actually be lost, causing the image to degrade in quality.
PNG format is similar to the GIF format in that it supports transparency and works best with solid-colour images but it’s superior to the GIF format as it has the ability to support true levels of transparency for coloured areas. Transparent PNGs
are currently not in widespread use on the Web because older versions of Microsoft Internet Explorer do not support them; however, they’re often used in Macromedia Flash movies. PNGs can produce a better quality image at a smaller file size than can GIFs."
thats a webmaster's point of view but it comes down to what ever floats your boat
