The alignment with solution scope is the first consideration for filtering ideas, as it ensures that the proposed features are consistent with the business need and objectives that the solution is intended to address. The other considerations are also important, but they are secondary to the scope alignment. For example, a feature that is low-cost and fast to implement, but does not align with the solution scope, would not add value to the solution or the stakeholders. References:

CBAP / CCBA Certified Business Analysis Study Guide, 2nd Edition, Chapter 9: Solution Evaluation, page 343

[BABOK Guide], Section 7.6: Assess Proposed Solution, page 268