For those who want direct access to the Arch repositories (unlike Manjaro), I'd recommend trying out Antergos. It shares Manjaro's vision of making an Arch experience more accessible, however it differs in that it is indeed, true Arch Linux. Both Manjaro and Antergos post updates about periodic releases on their blogs, however these are more or less just milestones than actual release dates.
Flashing back to fixed release distributions like Ubuntu, it's easy to see why Linux users might find the idea of a rolling release appealing. Imagine never again needing to worry if your distro is about to hit "end of life" like we've seen with older releases of Ubuntu. On the surface, the idea of using a rolling release distro is certainly appealing. But what are the downsides?
Ubuntu, while far from perfect, tends to see a lot of release testing before it goes live to the world. With a rolling release, you're that team of testers. Now to be clear, rolling releases like Arch and Debian have both stable and testing repositories. This means packages from the stable repositories should be perfectly good to use. And if you're an experienced Linux user, this is the way to go.
For the less experienced Linux user, Ubuntu makes reverting to the previous release a preferred course of action. Using Ubuntu, one doesn't have to know why something doesn't work. Purists will argue that this mindset is unhealthy and leads to that user never developing into a more experienced enthusiast. I would counter that most people honestly don't care why something doesn't work, rather, they simply want it fixed.
To revisit the section on package downgrading vs. reverting to an older release of a distribution, it really comes down to this.
-Ubuntu (and derivatives) are great for anyone who just wants their computer to work. If the latest version fails for some reason, they're free to revert back to an older release without needing to determine why the failure is happening in the first place.
-Arch (and derivatives) happens to be the goto distribution for anyone who wants to enjoy the latest bleeding edge software, in addition to maintaining close control over each package that's installed on their PC. This is perfect for those who understand why a feature is suddenly not working, and are willing to decide which package needs to be downgraded to address the issue.
So now comes the big question: which distribution type is more stable, a rolling release or a distribution with a set release schedule? No Linux distribution is going to be 100% stable, there are too many variables that can happen between the Linux install and the end-user. That said, Ubuntu does better at not being updated regularly than a rolling release distribution.
I've had Ubuntu installs that needed to be upgraded, were badly neglected and then only packages were updated much later. When trying the same thing with a rolling release, things can indeed break. To be clear, this isn't the fault of the Linux distribution, this is the fault of the end-user.
My advice is to use the above information as a guide. If you're someone who loves to tinker, and wants to enjoy a deep symbiotic relationship with their OS, go with the rolling release. If instead you simply enjoy running software and running various tasks on your PC in a consistent environment, Ubuntu may be your best bet.