Confederate sympathizers are more motivated to comment about Civil War generals than advocates of the Union cause.
Thomas Jackson has more votes that William Sherman.
Not to mention those who voted for Forrest.
With that said though, this question points me to only one answer and that is R.E. Lee, regardless of what I may feel about that.
As far as my personal feelings are concerned, I think that it is a tragedy in that many young Americans died because of it, but it is the only answer that I can give to this specific question.