Axios kinda waiting for xfce but may stay on budgie
I like Budgie, my first Solus DE, and I even used to be a Budgie evangelist. I created lots of flash drives with the Budgie .ISO on them to give to family members, co-workers, and other friends. But Budgie has always had a serious limitation that keeps me from continuing it use it on my hardware - its limitation to just 8 virtual deskotps No other DE that I know of, on Solus or elsewhere, has such a limitation. That's what originally sent me to Plasma, where I've stayed until now.
My workflow is such that I don't like the applications I use to have to compete with other applications on the same desktop. Thus, Thunderbird has its own, Vivaldi has its own, Terminology has its own, and so on. For a long time, I used 10 virtual workspaces, and last year I added one more, when I started using Telegram a lot. 8 simply don't allow me to work the way I like to.
I think you'll be very impressed with Xfce, based on the time I've spent with it so far. There are still a few nits to pick with it, but nothing really serious, IMHO. If I were asked to rate the Solus DEs from best to worst (for me), it would be Plasma, Xfce, Budgie, and GNOME. And Xfce certainly wouldn't limit me to 8 workspaces.
If you liked using MATE, I think you're going to love its replacement - Xfce - when you get a chance to try it.