On Fc25 Gnome, the default is set to Wayland. It changes when you install proprietary drivers on a hybrid GPU driver system (KMS intel driver + proprietary driver). On the proprietary nVidia drivers, Wayland does not work, it's not a KMS driver. On the Intel iGPU, Wayland can work, providing you don't load the nVidia driver. If you use nVidia proprietary drivers, system security is a joke, so you shouldn't really bother, because SELinux is shot and you have pretty dodgy binary blobs in your kernel lol.
Ubuntu, like Fedora, has a pretty decent core. Ubuntu Core is not bad by any stretch of the imagination. But just like RedHat's "official" Fedora Workstation and Server distros, Ubuntu's official Ubuntu distro (so with Unity), is not the best implementation of Ubuntu Core. I personally prefer Fedora, I use Fedora KDE mainly, which is a community spin, the Fedora equivalent of Kubuntu on Ubuntu Core. The difference is that Fedora is all open source and free software, Ubuntu isn't, and thus the Fedora repos are pretty safe to use and high quality, also because of the RPM packaging format, which is more stringent in terms of quality assurance than the DEB packaging format. The Ubuntu repos are a mixed bag. The core packages are just fine and very well maintained, but Canonical also offers non-libre packages, which is one thing, but what's worse, it also allows third parties to directly pull into their repos, for instance, the packages for Chromium are maintained by a dude sitting at Canonical, but on Google's payroll, he works for Google, and is not interested in open source quality control nor open source safety and freedom, and Canonical does not check what he does. Chromium was actually, despite the fact that it's basically open source software that is enough unencumbered to be on the Fedora repos, removed Chromium from the Fedora repos, because Google just cuts too many corners, breaking the upstream (which is of course more challenging than with Ubuntu as Fedora is bleeding edge), repackaging old packages to make things work, etc... basically practices that don't belong in open source software development. For Canonical, this is not a problem, so that means it might be a problem for the users.
I use both Fedora Core and Ubuntu Core based distros, mostly community spins, mostly KDE based. I use Fedora KDE spin and KDE Neon LTS, which is a LTS version of Kubuntu with more modern packages, it basically IS Kubuntu, Neon is not an actual distro, it's more like a repo polishing service if anything.
There is a big difference in where I use different distros. I also use Arch and Gentoo and Debian and OpenSuSE and SLES, I even have a slackware box (and BSD boxes).
KDE Neon is pretty awesome for general use and Android type development stuff. Fedora is the best development distro out there bar none, it has the most tools available in latest versions, it has all the Eclipse and Atom plugins in latest versions, OpenSuSE/SLES is pretty amazing for system management, server applications, hybrid environments, data security, and virtualization using all kinds of different hypervizors.
There is no one distro "better" than another. Everything is choice. You just look for the compromise that fits your use case scenario, or you go to SuSEStudio and make the perfect unique cocktail for yourself.
It's also a practical thing. You can totally install a new distro without formatting your /home partition, so even your Firefox settings and bookmarks are saved, as well as your customizations etc, and installing a new distro takes like 4-5 minutes on a modern system, so if you reach a blockade, because something doesn't work like you want it to, you make the decision on whether to invest 20 minutes and solve it, which is also educational of course, or, if you don't have the time or just don't feel like it, you throw on another distro and continue where you where blocked in 4-5 minutes.