I like Kevin, he's kind of an asshole but in a "tsundere" kind of way, if that makes sense. Plus he's the hottest. But I also really like Norman an David too, they're great!
I can't tell you who I like best cuz I haven't been able to complete any route other than Thomas because you refuse to put out any sort of guide or hints for the other routes.
Zac is an interesting character. I've only ran into him thrice, but the little I picked up makes me what to learn more about him. Is there more to more of him? Regardless, Ian is the guy that I felt happiest with.