I'm not a student of Levinson's, but I've played for him a number of time in masterclasses at Juilliard, and I concur with with Justin said about him. He's really a very compassionate person and a great teacher.
I'm also not a student of Laszlo's, but I've played for him several times, too. He's very nice and does work a lot on the right hand, general posture, movement, etc. I'd definitely say that the kids I know who are studying with him enjoy and are benefitting from his teaching a lot.
As for Hanulik, I've met him only once (when I visited UCLA). I didn't play for him, but he seemed like a really nice guy if that's worth anything. He studied with solid people, too.
I've only heard about Bransby - I had a lesson with Rob Kassinger about a month ago, and he studied with Bransby at Aspen when he was doing a fellowship there (he had classical & jazz fellowships concurrently!). He told me that he thinks Bransby is great.