On the subject of Star Trek characters, there are a few pretty good ones: Martok, Damar, Dax, Kor, Kang, Morn.
But the only two who are actual, believable, fully fleshed out, 'real people' are Obrien and Worf.
Mostly because even through the very obvious exteriors of honor-obsessed idiot and miracle worker, they both operate in a very realistic way. They get drunk and talk about women, they remember the horrors of the battles they've fought and unlike characters like Picard, Riker and Sisko they don't go around pretending to be better than everyone else. They know the nightmares will never stop and that life will never be easy, but they know they've got no choice.
