I actually like Butters. He's pretty funny.
One of my favorite Butters eps. is the one where Cartman & the guys plan to infiltrate a slumber party, and decide Butters would make the best girl.
Cartman fakes Butters' death (he tosses a pig carcass off the roof of a building), and Butters appears at school as a new girl, "Margerine." Butters (or Margerine) is invited to the slumber party while the boys spy outside the house. At first the new "girl" is shunned, but is ultimately accepted, much to Cartman's disappointment. When Butters returns home (as himself), his parents think he's returned from the dead, and chain him in the cellar.