They're both obnoxious, bigoted, jealous, petty, and hilarious. Plus---
Cartman: Too bad drinking scotch isn't a paying job or Kenny's dad would be a millionare!
Draco: Longbottom, if brains were gold you'd be poorer than Weasley, and that's saying something.
Other favorite quotes:
Cartman: You have rats in your house, too, Kenny?
Cartman: Seriously, you better stop being so poor or else I'm gonna start huckin' rocks at you.
Goth Kid: To be a non-conformist, you have to dress in black, and listen to the same music we do.
Reporter: This week a boyscout leader has been apprehended for taking sick child pornography pictures, which we will now show you.
Dr. Hallis: Look, us plastic surgeons have one philosophy: if we can help someone's self esteem a little, then why not do it if they have three thousand dollars?
Mr. Garrison: And, so, children, that's how you tell a prostitute from a police officer. Now, are there any questions? Yes, Kyle?
Kyle: What the hell does that have to do with American history?
Mr. Garrision: Good question, Kyle. Are there any other questions?
Kyle: Mr. Garrison, I'm the only one here. Everyone else has chickenherpes.
Reporter: Do you actually believe in the ladder to heaven?
Guy: If heaven is an eight year old boy...and the ladder is my penis.