CloudFormation has an “easy button” if you are part of an organization with a business support plan from AWS. If you can’t figure out something you can submit a ticket and start a chat.
Also CF is the “native” language of AWS. There are plenty of getting started examples from AWS where they give you the template. Also Elastic Beanstalk extensibility is built on top of CF.
Not to mention Codestar that will set up environments for you for common use cases and exports templates and the lambda environment lets you configure everything from the console, test it and then you can export the CF definition.
Like one sibling comment mentioned, getting support from AWS is nice. You can buy Terraform support, too, but knowing HashiCorp it'd probably cost more than most peoples' AWS bills in their entirety. (This is me being a little cheeky and unfair—HashiCorp handles community support via GitHub Issues for Terraform really well.)
CloudFormation's built straight into AWS, so there's no need to set up state file storage or locking or worry about a state file at all, really. This has its own set of drawbacks, but it's nice for getting started, and in theory it makes CloudFormation more robust out-of-the-box.
CloudFormation StackSets are really nice if you have identical resources that need to be placed in many different regions and accounts. (Example: we use it to place GuardDuty and Config, both regional services, in every region.) With Terraform, this means copy-and-paste, as far as I know, though maybe Terraform 0.12 sets up the groundwork to make this better?
The Service Catalog is basically a way to let technical end-users manage products via CloudFormation templates. Something could be built to do the same for Terraform, but I don't think there is anything like that right now.
CloudFormation does (attempt to) roll back to a known-good state if an update fails. Terraform just stops in the middle of what it was doing. I have mixed feelings about that.
I find YAML to have better tooling/editor support than HCL, though I actually prefer HCL.
There are existing CloudFormation wrappers (e.g. Troposphere) that can give you a full programming language on top of CloudFormation. To my knowledge, there isn't anything similar for Terraform.
Some things that have changed with 0.12:
CloudFormation has had `AWS::NoValue` for as long as I can remember. Terraform <=0.11 had special values (like empty string, number zero, etc.) that were special-cased as no value. Terraform 0.12 now has `null` properly.
Terraform <=0.11's ternary operators were maddening because both sides were evaluated, which led to errors, unlike CloudFormation's !If. In Terraform 0.12, the ternary only evaluates one side.
Cloudformation will leave your infrastructure in a consistent state. Period. It will consistently drive things from point A to point B or rollback to point A if it cannot get to B. It will also correctly remember all the resources it created and allow you to properly identify them and/or delete them. These sound like tablestakes but Terraform cannot do this. Add the frustrations of HCL on top and it’s a big no go for me.
I've had CloudFormation fail to roll back plenty of times, though never in a situation where it actually mattered.
I've never had Terraform "forget" resources or disallow me from deleting them (unless I requested that). Maybe those are bugs that've since been fixed?
It sounds like we've had very different experiences with these tools.
My experience with CloudFormation has been consistent with what you just said. CF will fail to delete resources and then lock them in that state, requiring AWS tickets and reps and all that. I have not had anything like that in TF.
