What group/HR function owns the delivery of and overall content for new employee orientation/welcome materials (ie, strategy and brand awareness, benefits information, VALUES)?

This is managed through our onboarding program managers who sit within Learning & Development. In past company (smaller), TA owned the coordination of onboarding, and therefore the distribution of materials, swag, touch points, etc... 

New employee orientation is a crucial process which may need collaboration of various functional teams like HR Ops, Internal Communications, Business etc however is good to have one team taking lead and accountability for content which ideally could Learning & Development. 

In my experience Orientation is a collaborative effort between HR and IT. A new user cannot hit the ground running without either team providing taking part in onboarding. 

Feels important to highlight that there might be differences between who's the owner of the content (ensures is updated and still relevant) and the owner(s) for updating and delivering the contents. 

Usually the Learning & development manager, according to a specific checklist for new employees, is responsible to deliver the training, the orientation materials (policy, information, internal regulation, strategy awareness) and so on...