Spiderman 3 or Transformers ?

[GooseGaws]

Also, both releases are two-disc sets which would indicate a comparable level of extras, though extras are obviously determined solely by the production studios and not in any way by the size of the discs.

 EDIT:  The Transformers HD-DVD also has several HD-exclusive features, while the Spiderman 3 Blu-ray has no HD-exclusive features.