By coincidence, I took a photo of the same topic, horizontally and vertically. I specifically tried to get the reflections of the leaves and trees in the canal. Not sure, which one is the better of the two.
Photography 101: Water
New / Amsterdam
A mother / daughter blog covering two continents
New / Amsterdam 
I like the vertical. The reflection on the water and the water itself present a leading line to the bridge. Or basically, it just draws me in more.
Thank you for looking at the photos and providing these instructive comments!
I like the horizontal image. To me it looks like it has more depth and the colors are more vibrant. The only change I would make is to level the horizon. The bridge looks like it is slanted. I know it’s minimal but still visible. Great vantage point!
Thank you for your comments! I straightened the photos, I hope.
Yes straight looks so much nicer, great!
I prefer the horizontal too, by just a bit.
Thank you for your input!