Butters, Cartman and Kenny.
Butters because he's so fricking cute and I'd adopt him if I had the chance.
Cartman because he's a good character and I love his catchphrases (my favourites are "Screw you guys, I'm going home!", "But miiiiimmmm!" and "Respect my authoritah!").
Kenny because despite his dirty jokes, he's actually a really nice kid and he genuinely cares about others.