There isn't really a most 人気 PERSON. Just a most 人気 group. Most of them are pretty nice, I'm just not really フレンズ with them. A couple of them are just... >:(
There's a couple of really 人気 people, but probably the most 人気 is the girl who's locker is 次 to mine. I don't know her very well, but her entire attitude just seems fake to me, and her and her boyfriend are always having a make out session in front of my locker. So do I really like her? No.