I love fish that are more elegant predators, that is they prefer to take another fish's life in a single gulp (aros, dats, predatory cats), and none of them do it better than pbass do. I love the incredible speed with which these beasts inhale their food, along with their propensity to fill their mouths to the brim (nothing better, or worse, than watching goldfish staring at you from the brim of a pbass's full mouth.) Add to that the brilliant colors that they display, and the massive size (compared to most aquarium fish), and relative peacefulness and you have the complete package.
And as dmack mentioned, there is something to there stare...not sure what it is...but it sucks you in, begging you to feed them some more