I'm trying to set up a cycle of a few wallpapers, but it seems like there isn't a sizing setting that does what I'm looking for.

"Fit best and maintain aspect ratio (clip edges)" is almost perfect. However, when using horizontal adjustments, some wallpapers will have black bars on the edge.

Example One
Wallpaper: http://i.imgur.com/nnXoL5N.jpg
With fit best and maintain aspect ratio (clip edges) (bad - black bars):
With center (good):

Example Two
Wallpaper: http://i.imgur.com/2sXkbw7.jpg
With fit best and maintain aspect ratio (clip edges) (good):
With center (bad - very zoomed in):

Example Three
Wallpaper: http://i.imgur.com/be0HG4U.jpg
With fit best and maintain aspect ratio (clip edges) (bad - black bars):
With center (good - but slightly too zoomed in):

For now, I'm just using "Center" as it prevents the bars. But I don't like how some of my wallpapers become very zoomed in, so it would be nice if "fit best and maintain aspect ratio (clip edges)" would consider the horizontal adjustments I have on my monitors when resizing the image.

Any update on this? I would like something that doesn't zoom in and doesn't leave black bars.

That makes sense. Changing the adjustment order should fix this, which would be fantastic!

Keep me posted!