OVERALL: Blu-ray ALL

The US Complete Collection for the additional extras.

Note that there is a UK Amazon Exclusive that appears to come with the same bonus disc as the US Complete Collection, as well as a 16-page episode guide, a reproduction of Don Draper's "Why I'm Quitting Tobacco" letter, a letter announcing Sterling Cooper + Partners new logo, headed notepaper, art cards and an SCDP office plan.
However, it should also be noted that the US Complete Collection appears to be the only release worldwide that adds features to an existing season: adding commentaries to Season 6.

CUTS:

• Blu-ray ALL Complete Collection America- Lions Gate Home Entertainment - No cuts (683:33).
• Blu-ray ALL The Final Season Part 1 America- Lions Gate Home Entertainment - No cuts (332:57).
• Blu-ray ALL The Final Season Part 2 America- Lions Gate Home Entertainment - No cuts (350:36).
• Blu-ray B Part 1 Scandinavia- Future Film / Noble Entertainment / Star Media Entertainment - No cuts (332:19).
• Blu-ray B Part 2 Scandinavia- Future Film / Noble Entertainment / Star Media Entertainment - No known cuts - however, some episodes appear 20-30 seconds shorter than the US release (348:35).

Do you own a release not listed? Then please visit our forums and let us know!

Comparison added by Markus_Lang on 30/11/14
Comparison last updated by Rob_Hunt on 18/01/20

UPDATE LOG:

30/11/14: Initial entry
05/12/14: Updated title.
21/10/15: Addition of US Part 2.
16/11/15: Added Scandinavian Part 2 release.
16/07/18: Updated USx2.
18/01/20: Added US Complete Collection.