When considering buying Infrastructure as a Service (IaaS), there are several key factors to take into account:

1. Performance and Scalability: Evaluate the provider’s performance guarantees and the ability to scale resources up or down as needed. It is important to ensure that the provider can meet your current and future performance requirements.
2. Security: Understand the provider’s security measures, including data encryption, access controls, and compliance certifications.
3. Cost: Compare prices and costs of different providers, including data transfer costs, storage costs, and costs of additional services. Evaluate the cost-effectiveness of the IaaS provider based on your specific needs.
4. Provider’s reputation: Research the provider’s reputation and track record in the industry, read customer reviews and testimonials, and ask for references.
5. Service level agreements: Understand the provider’s service level agreements (SLAs) for uptime, availability, and disaster recovery. Assess whether the SLAs meet your requirements.
6. Support: Evaluate the provider’s support options, including the availability of a dedicated account manager, self-service portals, and 24/7 support.
7. Provider’s location and data sovereignty: Consider the location of the provider’s data centers and whether they meet any legal or regulatory requirements for data sovereignty.
8. Integration and compatibility: Evaluate the provider’s integration capabilities, including APIs, SDKs and compatibility with your existing systems.
9. Provider’s Expertise: Look into the provider’s expertise and their industry specific solutions if they have any, to understand if they align with your use cases.
10. Long-term vision and roadmap of the provider: Understand the long-term vision and roadmap of the provider and see if it aligns with your organization’s vision.

Ultimately, the best IaaS provider for your business will depend on your specific needs, budget and security requirements. Carefully evaluating the providers based on these considerations will help you find the best solution for your organization.