It’s up to you however the UI is looking forward and yaml is looking back IMO. You can easily backup the UI Lovelace file - it’s in the config/.storage/lovelace file. It is also backed up in a snapshot.
UI is fully functional like yaml with the benefit of being able to edit from the GUI. It’s really only a matter of what you prefer. HA is becoming more and more graphical though…
Sorry for late answer and thanks both for advices I agree with @jwelter and some stuffs have to be done with yaml, so I started with the GUI for basics and now when I need something more tricky, I do it in yaml