I agree with PrincessKisa. Having this name myself, the only spellings that I am fond of are Brianna and Briana, although I prefer Brianna, given the fact that that is how I spell it. I will be honest, I hate this spelling and I think it makes no sense. I am sorry if you are a big fan of it, if you are a Bryanna, or if you are quite friendly with a Bryanna, but I think this is a stupid spelling and I recommend Brianna or Briana to anyone who wants to name their daughter this.
It appears that this name should be pronounced ''brie-A-na'', which is a butt-ugly name, and even the nicer pronunciation, which doesn't seem logical with this spelling, ''bree-a-na'', doesn't stop the name from being tremendously boring, common, bland, predictable, lazily out together, and a name that seems to lack sophistication and elegance.
Amazingly, since this looks like a recent invention, I found an 18th century English bearer of this name as a middle name - her forenames were Mary Bryanna. Perhaps among her parents' relatives or friends there was a person surnamed Bryan after whom she was named. I think it's a pretty name.