We selected a tool AFTER we had a defined service catalog and specified processes.

The selection process went through the following steps: 

• >40 products long-listed and evaluated against “preselectioncriteria”.
• 6 invited for a detailed evaluation using technical questionnaire (>300 ‘questions’).
• For top 2: technical challenge presentations.
• For top 2: live instance tests performed.
• 6 reference visits performed
• Commercial, TCO, and planning considerations
• Service-Now selected

Arguments for Service-Now were 

• Functional Coverage
• Architecture
• Flexibility
• 100% Web Based
• SAAS (TCO and implementation speed)