The code differences between ElasticBeanstalk and Fargate are not very far, but JUST far enough to be annoying.

Because you've worked with Beanstalk in the past, I would personally stick with it unless I'm looking to fight 2 issues at the same time - Learning Fargate & Learning CDK/CloudF/Terraform.

Fargate is not a panacea - Elastic Beanstalk does have very cool options/features.