I can’t count the number of times I’ve seen complaints about the REAPER default metronome sound. Usually the complaint comes from someone that has moved from another DAW after many years, I don’t like it either.
It is easy to change though. I recently posted a video on making an audio click track using the Insert Click Source function. You can also select a new sound by RT-Clicking the Metronome button in the main toolbar.
After you load the new sounds don’t forget to update your default project template to keep the setting for all new projects.
Here are some metronome samples from other popular DAWs.