deploy controller and copilot using iam role based or keys?

when deploy controller   in console for example aws  which will be best practices to use either

1.  deploying controller using aws iam role based 
2.  deploying controller using access and secret keys that let us run the infrastructure as code
3.  can be use both at same time for example having 2 aviatrix account each one use iam role based and other use keys