Telephotos don't really heighten my sense of creativity but wide-angles do. Obviously, the subject often dictates the appropriate focal length but, that aside, a wide-angle perspective is, to my eyes, usually more interesting than a telephoto perspective. So, from my limited selection, the Sigma 12-24 is the lens that imbues most inspiration in me.
I think I'd suffer inspiration overload if I were fortunate enough to have a TS-E 17mm.