The Fab 5 and Catching Hell aren't officially part of 30 for 30 but are excellent.
My fave is The U followed by Reggie Miller, Colts Band, and Guru of Go. Disclaimer: I haven't watched them all yet.
"The Best that Never Was" is my favorite. One hell of a story.
I thought that was one of the most uninteresting stories they told. Great athlete, couldn't handle big time pressure, and then just faded away. His videos from HS were incredible but they really had to stretch his story to get 2 hours out of it..