In accordance with many, I think Ubuntu has a large user base and this means It's easier and faster to solve all the problems that may occur to a newbie without having to subscribe any community forum. On the other side, Solus forum is friendly and responsive, so this is a relative issue.
The repository isn't as big as well, and here something could be done; but, again, all the applications (I've tried) work well. Ie: Abiword has all the export modules, while in elementary Os it can save files in the native format only... DisplayCAL puts the measurement window perfectly in the screen centre while in Fedora 29 it appeared randomly, thus unusable, since in the screen corners gamma and even colours are different. In elementary, the window is movable but it drags around part of the wallpaper beneath it.
The integration of programs in Solus is also very good, clearly verified, and it doesn't happen, like sometimes on community maintained repos, to find programs with black icons on a black background like in Manjaro.
On the contrary what I like in the Manjaro repository is that's up to date: applications version is always the last one and you can download Scribus 1.5.4 instead of the 1.4.6, but also the latest Xsane. Even if it's not been developed since 5 years ago, it's still the only quasi-professional scanning app available for Linux. You can do nothing with Simple Scan, I'm sorry.
Solus is, indeed, stable, compact, consistent, reliable, it does not betray you, and you can quietly use bleachbit in SU mode with no risk to collect 1.000+ errors after the next system update as in Manjaro. And Solus, Solus Budgie is the best, has a familiar desktop where to (may be temporarily) past files picked up here and there, which is very handy, unlike the Apple/Android/Gnome3 Launchpad that doesn't have any.
At the end of the day, after having tried out at least 12 different major distros, I feel comfortable to suggest Solus to any newbie.
