Well, the main reason I have it in tallscreen position is mainly, as you can see, because it doesn't really fit on my table. But since then, it has really grown on me. Both positions have their uses. In a normal widescreen, you can watch movies and play games, and you can have two tasks side by side easily, but the tallscreen is great for coding or browsing long websites since you can see twice as much.
Dell monitors are all very good quality wise. They're a bit more expensive compared to some other ones, but they are definitely worth the money if you can afford them. The one in the screenshot is almost 3years old now, so I'm sure you can find better ones now. But yea just any Dell monitor is amazing, both in image quality and in position customization. You can put then at any angle, height and tilt you want. My middle monitor on the other hand, which I got for pretty cheap, has a pretty high screen resolution (2048x1152), but doesn't move at all in any way, which is pretty bad.