in terms of what i'm into when it comes to BL manga, i have a couple things i look for:
-original story and unique characters -well developed and complex characters -psychological without being too dramatic -unusual or unique art (at least memorable and distinguishable from typical yaoi style) -low on melodrama -doesn't glorify or romanticize sexual violence -gets away from typical seme-uke dynamics (bonus points for a good verse story but those are few and far between) -funny!