I strongly prefer the spelling Brona, and I find the name cool, even though I'm not happy about the religious history of it. I'm not superstitious, so I don't really care what it means, but the trouble is that if you're an American female named Brona(gh), your name has the unfortunate element ''BRO''. Not good. Not the best name to have in the US, too bad.
In the book Two Doors Down by Annie McCartney, the main character, Sally O'Neill's daughter is called Bronagh. Personally I like it because of its oddity, but it's not one of my favorites since it looks like it's pronounced "bronag".