here's the reasons.
1.it's the longest-running sucessful popular show on cartoon netowork up date.
2.it's my favorite show of all time on cartoon network and 3.it ended on a good note with the movie big picture show when it ended in 2009. and i watched this show until it originally ended from season 4. and came back with seasons 5 & 6 so this was my favorite show of all time!

My main reason is because it's really funny.