Ok, I can try Solus. As long as the only meaningful difference is the package manager, I should be able to use it.
Also, I didn't find the Manjaro spin but on Budgie's official website, there is a list of distros that come with Budgie. So, I can try those if, for some reason, can't use Solus.
I love my Xmonad. I haven't customized it except for one thing for fullscreen windows. I have no widgets or toolbars or desktop icons or anything besides dmenu as a launcher and xterm for everything else. And I love it. However I have some subtle graphics issues like screen tearing when watching certain 4k content, hidpi scaling issues that I could never resolve for all applications and sometimes my GPU doesn't like my TV (which is my main monitor). These are likely the fault of nouveau, but I wonder if Wayland will fix them.
I really wish XMonad would support Wayland. I don't need it to, but gnome on wayland was just really really smooth. Maybe I can set up another window manager with the exact same key bindings on wayland, since like I said I don't customize it at all.
Xfce
I've daily driven every major DE except KDE (GNOME, Xfce, MATE, Cinnamon) and I always ended up switching back to xfce. I'm not a fan of GNOME's workflow and since it's not that customizable without extensions, that made me switch from it very quickly. I used Cinnamon on Mint for a few months and while the experience was mostly fine, it sometimes felt a bit laggy. As for MATE, while I love the GNOME 2 layout and it's a relatively lightweight DE, I encountered plenty of visual bugs there and I could very easily replicate that GNOME 2 layout on Xfce (without a system menu, but still).