There’s no industry preference regarding ornaments that signal scene breaks. Pick one that makes you happy. That said, I recommend something understated so you don’t distract editors from your fab content. Plus, cutsey things like the Wingdings 2 scissors image can create a subtle impression of unprofessionalism. No matter your specific choice, do use something. Often, manuscripts I receive for editing lack these visual signals, and in almost every case I experience at least one moment of confusion when a scene break lands at the bottom of a page. That might not have been the placement of the break when the author sent me the document, but my editing lengthens and shortens chapters unpredictably. Don’t do that to your future editor. Insert ornaments while you draft as a matter of course.
Is a single character best? Print journalism uses (or used to use) three spaced hashes (# # #) to indicate the end of a story, and some compile settings in Scrivener still have that. Should multiple ornaments be avoided?
I use 5 underlined spaces centered, Never had an editor have a problem with it.