Well I've already read plenty of one-shots (never a series, I guess I'm just lazy to download them) from both sides, so if I were to take my pick, I'd rather choose shounen-ai and shoujo-ai.
I can't stomach all those smut scenes in yaoi, but I do appreciate the occasional, hard-to-come-by, well-written plot of a yaoi manga I encounter now and then. I just skip reading all those sex scenes.
I'd rather heart all those fluffy moments of BL.
Same goes for shoujo-ai as well. I've never read a real 'yuri' anyway, (yuri for me consists girl-on-girl smut as erotically drawn as yaoi), since most of the time, I'm reading cute, fluffy one-shots.
I think part of the appeal that yaoi and yuri have is that they present a more different take on a normal relationship, as opposed to a heterosexual one. And they're sweet and cute as a girl x boy pairing as well anyway.