Ubuntu MATE vs. Xubuntu for HiDPI screens
Starting with mate-desktop-environment 1.20 MATE desktop environment has true HiDPI support. HiDPI is be supported by default in Ubuntu MATE 18.04 and later. Every aspect of Ubuntu MATE 18.04, its themes, its applications, its icons and its toolkit assets have been updated to take advantage of HiDPI.
Xfce4 4.14 has true HiDPI support in Ubuntu 19.10 and later.