In this article, we have investigated different service models and provisioning steps of IAAS and PAAS solutions. PAAS providers indeed take on much more responsibility for your solution than an IAAS provider would. On the other side, IAAS may offer more flexibility at lower level (example: public IP addresses, load-balancer, etc.).
There’s no one-size-fits-all here. As a developer or architect, you should understand a customer’s need and determine the correct model to get the best possible outcome.