[Springtime]

SVG to me is always overlooked as a means to present not merely vector graphics but also other things like JPEGs with alpha transparency at a smaller size than equivalent, non-indexed PNGs for larger images (link a JPEG for the image and another JPEG/PNG/GIF for the mask, or both together as one image and use half for one and the other).

It's a rather flexible format, even if you're only embedding it within an img element/via CSS (ie: disabling its other possible functionality like video/JS/interactivity, though this comes at the downside of requiring base64'ing the embedded images, offsetting the some of the filesize savings...).

One can also utilize CSS animations within them (or alternatively SMIL in any Blink or Gecko based browser), whether embedded as an object or image.