I would have to say that my overall favorite type of decal is a static cling decal.
WHY.. Its decal that also is removable. I have seen static clings put on windows, plexy glass, bottle and more. I would totally recommend the http://www.123decal.com/static-cling-decal.asp . Yes, I do work there, but we sell so many static clings that it's no even funny. Fun yes…Funny no. The reason why static clings are so great especially at http://www.123decal.com is that we print with UV Ink. Therefore, they are enviormentally sound, they won't fade, and they hold up against the elements. We offer double sided static cling decals, face adhesive static cling decals, back adhesive, full color and many other types.
Take a moment and see why Static Cling Decals are my Favorite.
Tyler Hurst, http://www.123decal.com