When the little stream merges into the Sea, it is transcendent.
Vision to Blueprint
Blueprint to Roadmap
Roadmap to Plan
Plan to Solution
Value streams break into stages. Each stage decomposes into routing maps or can map to a process, process underpins capabilities (capability = people+ process+ technology) to deliver products/services and enable value stream stages. The value stream to capability mapping identifies the capabilities to be considered as you design your processes and stakeholder mapping identifies the roles required within that stage as input to process role definition. Finally, capability to information mapping provides input to information required by a given set of processes. A given capability can enable 0-to-many value stream stages. As capabilities are heat-mapped to determine if they are working well, not working, or non-existent. Capability maps to Business Unit (as part of organization mapping), Stakeholder maps to Value Stream (triggering stakeholder to stream and participating stakeholders to stages) and Process maps to Value Stream Stage.
Vision to Blueprint is critical in business transformation: Articulating the vision alone may be of value because it galvanizes people who previously didn't share a common goal. When planning a business transformation, EA should consider all impacts of the vision to the business - such as what new or modified value streams, capabilities, processes, data, org/roles, locations, applications, technologies, etc. are required and/or which of these exit in the environment. And then use capability map as the anchor or hub for understanding the connected view of all of these. And then a roadmap is useful to determine how to get there from here, but it is a fantasy if the "there" and the "here" haven't been identified
Blueprint to Roadmap, Roadmap to Plan, and Plan to Solution, all the like are necessary to bring vision to life. Value is tricky because it's subjective - in the eye of the beholder. So it's hard to identify an event that is always of value. One thing about EA is that you have to understand your customer and what they value, and adjust your approach to accommodate them. It is better to provide the systematic approach that works regularly when you're dealing with C-level execs and other senior stakeholders. Ultimately an EA must be part of delivering something tangible where the consumer of the vision, blueprint, roadmap, plan or solution (or whatever mutually agreed outcome) is willing to invest in its development.
Fair to say, all value streams listed above are important, and the importance differs depending on the organization. Some organizations already excel with rigorous repeatable processes in one or more of those areas yet leave gaps in others. In those organizations, EA should fill the gaps, so the gaps become the "most important."