Who says your best buds can't be drawn?
Big Gay Al
When looking at South Park characters, you really have to question who would you be able to tolerate being friends with on a regular basis. Randy Marsh would be cool, but no one would top Big Gay Al. He's super, after all.
Rick Sanchez
Would Rick be a lot to deal with as a daily friend? Yes, but he'd also bring a hell of a lot of entertainment into your life. What other 60-year-old cartoon characters are you going to hang with?