Ranking the current President is not a job for historians. By engaging in this popularity contest, they have simply revealed their political bias, as if we didn't know already.
Yeah, but think how it boosts their academic and collegial status! Gee, some might even claim credit for being 'daring' and 'cutting edge'. On the Reagan put-down, Schlessinger is permanently unavailable for comment, but I wonder if the vote may have changed now that a further 12 years (40 years total) perspective.
My personal view is that perspective will enhance George W, perhaps greatly.