Requirements before demos
Otherwise the best presenter wins.
Because the vendor wrote the script, and nobody had written the requirements yet.
A product demonstration is a performance, and the order of events decides the outcome. Organisations that see demonstrations before agreeing requirements end up choosing the most persuasive presentation rather than the best fit, then discovering the gap during implementation when switching is expensive.
Writing requirements first, with the people who will actually use the system, changes the conversation entirely. Vendors are asked to demonstrate against your script, scored against the same criteria, and compared on something other than how well they present.
The other half is who pays the adviser. A consultancy that also resells the software has an interest in the answer, however honourable the individuals. Holding no reseller agreements and taking no commission is a structural guarantee rather than a promise, and it is the only one worth anything.
Otherwise the best presenter wins.
No reselling, no commission, no partners.
Data protection law belongs with a solicitor.
A free first call, from someone with no stake in the answer.