The Optimal Acquisition Integration Approach?

In case of a merger or acquisition, what is the optimal integration approach? Actually there are 4 possibilities:
# Resource sharing. Value is created by combining the companies at the operating level.
# Functional skills transfer. Value is created by moving certain people or sharing information, knowledge and know-how.
# Transfer of general management skills. Value is created through improved insight, coordination or control.
# Combination benefits.
Source: Acquisition Integration Approaches.