I use Ubuntu because I want things to just work. I also want all the supported applications out there to have installation that are simple. Every important piece of software that I use has a easy method to install on Ubuntu. Spotify, steam, various music production software.
That being said there are some rough corners still. There are things that don't go as smoothly as expected. the last two releases seemed mostly focused on catching up with the transition back to gnome.
Each time a Ubuntu tries to create a solution in-house to similar ideas already being worked on it tends to fizzle out. Unity and mir come to mind. Snap may go this route as well.
I think ubuntu's strength has been in creating a rock solid well rounded distro that is stable, usable and well supported. Or at least that's the idea. Unfortunately sometimes they fall short of this. Unfortunately/fortunately, there is a lot of room for improvement for Linux desktoping. They have helped the cause though and i hope they continue working to smooth out the rough edges.