Great question -- but a hard one! At the school I went to, we hung out with a lot of the different frats, so I got to meet a bunch of great guys in each! It would be easier for me to name the one or two I wouldn't join...but I'll leave that alone
LOL
KA's - great guys and real gents -- I'm HUGE on being mannerable and gentile, so I guess this would be my #1.
Close seconds would be Delta Sig and Sigma Chi.