> PeaZip has a very clean UI, and nice green icons, so it’s very obviously the better choice.
If you're "opening" an archive directly you're doing it wrong. The beauty of 7-Zip is the shell integration where you can just right click an archive and do "Extract to [folder name]" or right click a folder and do "Create archive...". I have not had a need for the UI that appears when you double click on an archive in any archive program in 20 years.