It's been the best option for a while now on Linux IMHO. I was a long time SnagIt user on Windows and when I went Linux full-time, I tried all different options but the ability to snapshot and markup quickly are key.

Works well in XFCE, KDE Plasma, and Cinnamon - notso in Gnome because, well, Gnome. I wish it did video too. Until it does, I am using SimpleScreenRecorder - which is okay.