I also feel The Indigo DIsk to be better than The Teal Mask...
But my opinion revolves around the Pokemon available in those two DLCs.
The selection of Pokemon for Indigo Disk far outweighs the one available in Teal Mask. Gen-III starters are best in terms of utility, we also got HGSS covers, SM covers, BW covers there, whereas these all are missing there.
Archaludon is terrific, having the typing of Dialga, and some big bulk, which is nice.
Gouging Fire is fun, Raging Bolt is fun.
Whereas, the one which are there in Teal Mask have bad designs as well; Ogerpon looks weird and to me it felt that Wormadam like type variations under specific scenarios, but with control in our hands.