Persuasion: the "ends" have it.
A broad consensus of commenters and emailers says that the end is the point of most emphasis in a sentence. Strunk and White got it right.
Yet many acknowledged that it often depends on the context and goal of the writing. For example, I tend to think of the beginning of the sentence as the place for a "punch." But that's probably effective only in a new paragraph or in the first paragraph of a document. In general, the end of the sentence is the place for emphasis. As one commenter noted, the beginning of a sentence should generally connect to or build upon old information. The new information, which deserves emphasis, belongs at the end.