Generally, I often have trouble defining a personal "best and worst" of anything, and this is no exception. However, here are a few of my favorites, and less so...
The 2004 "Star Wars Trilogy" Release: Don't get me wrong; it's cool that we got any commentaries at all, and Carrie's opinion was nice to hear...but Ben Burtt talks way too much, and that's coming from a fellow chatterbox! It seemed like on any truly great scene, you'd expect to hear Lucas or Carrie say something about the story, but no...Ben jumps in with yet another piece of audio trivia. Now, I have a huge amount of respect for sound artists, but this is where a separate audio-related commentary would come in handy (Sony did it right, providing an alternate technical track for each of the "Spider-Man" films). Don't mix sound or VFX guys in with the actors; it jumbles all together, and ultimately crashes into a million pieces.
Now, as for commentaries I hold in high regard, the "Back to the Future" tracks by Bob Gale and Neil Canton were great, and in his defense, Gale tried very hard not to repeat anything he'd said on the other interviews. This shows a genuine concern for the audience's patience, which is always cool. The commentary on the director's cut of "Daredevil" was impressive as well.