TOD:
I can't think of any Criterion commentaries I've heard that I didn't think enhanced the viewing experience. Most of those commentators are such experts with the careers of the directors of the films that they bring in a world of detail into their commentaries.
As I've said on many occasions, John Fricke's commentaries on the films of Judy Garland are peerless. I've listened to each one multiple times because they are professionally put together, he has a nice, easy conversational tone, perfect for commentary. The late Ron Haver also had a a brilliant way of enhancing a film through his commentaries. The one on Criterion's SINGIN' IN THE RAIN laserdisc is sublime, and he did a wonderful job with their KING KONG, too. I'd much rather hear his commentaries for those films that the ones used on their DVD counterparts.