Run a bake-off
Three vendors demo, a scorecard gets built afterwards to justify the preference already formed, and the selection is made on presentation quality. The problems arrive during implementation, when changing course is expensive.
ERP, CRM, or a platform migration you will live with for a decade.
The people who understand the options best are the people selling them, and their answers are honest and incomplete in exactly the ways their products require. Meanwhile the requirements are being assembled from whoever in the business feels most strongly, the demo is being mistaken for the product, and the number under discussion is the licence cost rather than the cost of getting the company onto it.
The visible problem is rarely the one that decides how this goes. These are the parts that are true whether or not anybody has said them out loud.
Every question you ask is answered by somebody whose compensation depends on the answer. That does not make them dishonest; it makes their advice structurally incomplete.
The department that lobbies hardest gets its needs into the specification, and the quiet operational requirement that breaks the implementation is not in there at all.
Demonstrations run on prepared data, in configurations built to demonstrate. The gap between that and your data is where implementations overrun.
Licence cost is the visible number. Implementation, data migration, integration, training and the productivity dip are the ones that decide whether this was a good decision.
Three vendors demo, a scorecard gets built afterwards to justify the preference already formed, and the selection is made on presentation quality. The problems arrive during implementation, when changing course is expensive.
Get what the business actually needs on paper first, agree how you will score it before you see a demonstration, and make every vendor answer the same questions. The shortlist then means something.
The order matters more than the individual steps. Most of the cost in these situations comes from doing the right things in the wrong sequence.
Gathered across the departments that will use it, including the ones that do not lobby. Written as outcomes rather than as a feature list copied from a brochure.
Weighted, written down, signed off. Doing this after the demonstrations means building a justification rather than making a decision.
Your scenarios, your edge cases, your volumes. Plus reference calls with customers you found rather than customers you were given.
Licence, implementation, integration, exit. Including what happens at renewal in year three, which is where the leverage disappears.
Each of these has a real answer and a plausible one. Knowing which you are giving is most of the job.
What must this do that the current system cannot, in the words of the people who will use it?
What is the total cost over five years, including implementation and change?
Who inside the business is accountable for adoption after go-live?
What does leaving this platform look like, and what would it cost?