While I'm quite fond of highly imaginative (i.e. speculative) fiction for adults, I actually like more realistic YA, so that's usually what I'm looking for - and no doubt that's just because it's what I was used to growing up, so I'm constantly trying to recapture the days of rapture of my reading youth.
I try to stay away from trends for YA because once the trend is identified it's usually on the way out - although this may change as publishing time frames become shorter with more digital publishing (although children's/YA publishing probably won't move as quickly to digital as genre fiction for adults). So it's just the boring old finding-identity-in-a-small-town-or-bit-city kind of thing for me. I also love it when there's a dark edge to a story - genuine darkness, not a showy attempt at juvenile delinquency to suggest 'bad boy' behaviour - but it's often very hard to get those stories published. Adults, you see, don't like to be reminded that teenagers have a fully functioning awareness of the crappy things in life and, more specifically, the crappy things adults do.