Well, as I'm a bit of an expert on the subject (I've been a yaoi fangirl since before I knew what it was
) I can prove that there are great exceptions to the rule. I personally love bara much more than mainstream yaoi, even though I'm female, probably because the traditional seme/uke appearances irritate me. I mean, I'll still look becuase I'm addicted, but I'd much rather gape at two hunks locking lips, instead of a hunk and someone I mistake as a girl (becuase how is that yaoi?).
But both are mixed and combined endlessly. I've seen yaoi with no clearly defined seme and uke (based on size alone), and there are plenty of bara strips out there where the whole focus it the tender romance more common in BL. As a hopless romantic, that's my 'best of both worlds.'
So, as an answer, I love both!! But prefer bara with a touch of romance.