IaaS is the simplest way to move or create an environment in Azure because this provides more synergy with the on-premise model.  It can be the most costly as well for supporting resources, but the most versatile. Let's look at some pros and cons of using IaaS:

• Pros
  • More control over the environment
  • Simple migration to the cloud, better compatibility with legacy code
• Cons
  • Need to continue to patch OS
  • Need to support network configuration
  • Need more support in the environment