Do you want to style your SVG with CSS code? Use SVG.

Do you want to support IE8 or other browsers that don't support SVG? Use OBJECT.

Do you want to interact or animate your SVG? Use SVG or OBJECT.

You don't want interaction and no fallback without JavaScript? Use IMG.

For more information about SVG, please read this article: http://www.smashingmagazine.com/2014/11/styling-and-animating-svgs-with-css/