Transformers: Seeds Of Deception, a saga set (mostly) in the Golden age, before The War Within vol. 1, The War Within: The Dark Ages, The War Within: The Age Of Wrath.
Official books in the same continuity: Infiltration, Stormbringer, Escalation, Devastation, Revelation, Maximum Dinobots, Spotlight vol. 1, Spotlight vol. 2 and Spotlight vol. 3.
More details in the SoD roadmap!