Choose the function you need before comparing firms. A commercial representative, delivery marketplace, access platform and preparation contractor have different jobs, so a single undifferentiated ranking will hide important gaps.
Write a one-page appointment brief with the archive, intended use, decision deadline, exclusions and outcome. Then require each candidate to complete the same evidence table:
| Claim | Evidence to request | What it can establish | What remains unproven |
|---|---|---|---|
| We know relevant buyers | Permissioned introduction or dated procurement correspondence | A relationship and its scope | An approved budget or purchase |
| We have sold comparable data | Redacted executed scope and reference | Transaction experience for a particular use | Your archive's future price |
| Owners receive payments | Reconciliation plus permitted payment evidence | Receipt and distribution for that transaction | Future payment reliability |
| We handle permissions | Written responsibilities and cohort workflow | A defined service | Ownership of every item |
| We can terminate access | Demonstration and exit schedule | Behaviour of controlled endpoints | Removal of exported copies or trained influence |
The platform distinction is concrete: AWS documents both offer terms and a separate Data Subscription Agreement. Technical procurement does not remove the need to inspect the rights being offered. AWS — Product subscriptions in AWS Data Exchange
Ask two shortlisted candidates to demonstrate the same archive scenario. Record unanswered questions as “not established”, not as proof of misconduct. Seek an appointment that limits the initial commitment and assigns a review date.