Many tradeoffs are related to the desirable properties of the mechanisms being chosen from, for example:

• Which IPv4 and IPv6 functionality/connectivity is required?
• The cost of deploying dual-stack, versus IPv6-only with translation to communicate with IPv4 devices
• The cost to ‘the Internet architecture’ of a certain method, e.g. are relays expected to be deployed by every ISP, or even every site? How do these relays interact?
• Security requirements – is the method open to relay abuse?
• Ease of management – how is the transition mechanism managed?
• Whether dynamic IPv4 addresses on the client need to be handled
• Whether IPv4 NAT traversal is needed from the client
• Whether just hosts or networks need to be connected
• How the solution scales – is there just one point of failure? Is load-sharing or balancing supported?
• Resilience in the solution
• Who owns the transition components (ISP or end site)
• How the service is discovered or configured, if ‘plug and play’ is desirable
• Whether specific services are enabled, like multicast
• How optimal the routing is (or isn’t), e.g. whether there is any route optimisation method
• What performance penalty is suffered from encapsulation/translation methods
• Whether reverse DNS lookups are available for the method
• Accountability – how is usage reported and monitored, or identified?

There is no single, ‘best’ solution for all scenarios. Factors such as those listed above will determine which is best for which scenario.