Yeah of course there isn't THE right music for something like that, but I wouldn't say that it doesn't matter. If you put music in it, it does matter. Even if there is no direct impact on the quality of the shown work, you get some kind of a audio-visual experience by watching the showreel. And therefore I would choose some music that supports the video/editing.
But that's just my point of view, if you just want to fill the silence, any music you like is okay