Who

This is likely to be different depending on the milestone reached, the decision being made, and the risk associated with that decision. 

The first thing to be decided therefore is the position of the particular assessment within the project governance - i.e. does the assessment sit within the project team (a matter that the project manager handles and reports to the project board on), or is the Project Board looking to undertake this function either itself or by seeking an opinion that is independent from the reporting being given by the project manager and forms part of the Project Board's assurance process.  

Thereafter the skills set of the people, process or advisor assessing the options or proposals must be established.  It is likely that specific design training and/or expertise would be of value in assessing the information being given and in differentiating between alternatives.

For example: A common issue in design team selection is that many people do not feel they have the competence or confidence to differentiate strongly between the ability of different designers to design. This can result in them assessing the 'quality' aspect of the scoring in terms of the clarity and coverage of the written information submitted - their essay writing skill - rather than their potential to design a facility of lasting value.