Brandon Gap vs. Middlebury Gap going east to west:

http://www.bikely.com/maps/bike-path/MIDDLEBURY-GAP

http://www.bikely.com/maps/bike-path/BRANDON-GAP

(Select "Show" to see the elevation profiles.)

Brandon is more gradual, but also longer. it also dumps you way south of Middlebury. Look closely and the elevation graph for Brandon Gap where it starts to descend. The first part is super steep. I rode it in the other direction (west to east) when crossing the country. It was the only pitch I almost had to walk.