We are not generaly against the use of GUI apps. But in case where something goes wrong, we recommend those, because they are known to work. In this case, as we have negative experience witrh tools like UnetBootin and we don't know if Rufus works, dd is a good example, so is apt vs. Synaptics e.g.
dd is quite simple:
dd if=/path_to_your_image of=/dev/sdX sync
where X is your usb-stick.