I've already used Solus for a while, but out of curiosity went on a spree of distro hoppning (and not by using VM's mind you, to get the full experience of issues on my actual hardware and the true sense of their performance).
Fedora 27 KDE
- The best KDE yet from what I can tell (sans the upcoming Solus KDE which I haven't tried). Feels more "KDE default", more confident, and less hipster/enthusiast than Manjaro which is a good thing. I think Fedora also hits a nice balance between stability and freshness with their release schedules. However, I ran into trouble with KMail soon enough (aka day f'ing one), which couldn't even be resolved by creating a new user account and reinstalling KMail. Jesus. Overall, KDE feels overly complex not for Fedora, but for the KDE team themselves. I hope Solus 4 KDE is going to keep it simple because I feel like KDE is demanding more than usual from the distro developers than usual desktop environments due to its complexity. Fedora KDE also had a nice looking theme applied, but it couldn't be completely restored if you temporarily changed to another theme and back again. Basically lost forever unless you went to manually edit/restore KDE core files. Huh. Again, maybe a victim of KDE's let's say technologically demanding customization.
Ubuntu MATE 17.10
- It's nice if you like the "good old days" but to me it's both a blessing and a curse. MATE has very well proven design with low resource requirements (read: fast on modern hardware), but the interface is heavily menu oriented and I think sometimes feels cluttered. Still, with some earlier so-so experiences with Xubuntu compared to Debian Xfce and a general distaste for GNOME 3, I think this is the only *buntu I'd be willing to use.
(and Arch Linux) - Yay, rolling! Right? It does feel Arch'y and of course it's always nice to be "in control" of even the details, but I've come to discover that these kinds of Linux distros often only transfer a labor of configurations to the user where the configurations are still always the same. Many of the "in control" advantages are illusions. For example, in Manjaro I for some reason had to set up my keymap to my Swedish layout. Yay, I'm in control here, so I will venture on this command line job to set "just the right" keymap for terminal windows! Or with Arch Linux itself; "Yay, I'm in control of configuring my Wifi so that it will auto-start with boot!" No. This isn't "being in control" in the good sense. At all. This is about manually doing what a script could do automatically and still add zero "cruft" to the end result. Manjaro had a bit of that, Arch even more so.
I still prefer Solus the most and plan to return to it soon enough.
Maybe in time for Solus 4 which seems imminent anyway. Now I know a bit better what the grass is like on the other side anyway, and it's generally not that green. Solus has an especially attractive combination of stability, speed, and using rolling releases without all the bad things about some other distros being rolling.