I get around most of the if stuff using "for each" to iterate over a map. That map might be config (usually from the hiera data provider) or the output of another deployment. It's not generally a very flexible "if" that you need most of the time, it's more like "if this thing exists then create an X for it", or "while crafting X turn this doohickey on of that data set has this flap", which can be accomplished my munging together days with a locals var for loop (which support if statements).
Honestly, I only use terraform with hiera now, so I pretty much only write generic and reusable "wrapper" modules that accept a single block of data from Hiera via var.config. I can use this to wrap any 3rd party module, and even wrote a simple script to wrap any module by pointing at its git project.
That probably scares the shit out of folks who do the right thing, and use a bunch of vars with types and defaults. But it's so extremely flexible and it neutered all of the usual complexity and hassle I had writing terraform. I have single handedly deployed an entire infrastructure via terraform like this, from DNS domains up through networking, k8s clusters, helm charts and monitoring stack (and a heap of other AWS services like API Gateway, SQS, SES etc). The beauty of removing all of the data out to Hiera is that I can deploy new infra to a new region in about an 2 hours, or deploy a new environment to an existing region in about 10 minutes. All of that time is just waiting for AWS to spin things up. All I have to do in code is literally "cp -a eu-west-1/production eu-west-2/production" and then let all of the "stacks" under that directory tree deploy. Zero code changes, zero name clashes, one man band.
The hardest part is sticking rigidly to naming conventions and choosing good ones. That might seem hard because cloud resources can have different naming rules or uniqueness requirements. But when you build all of your names from a small collection of hiera vars like "%{product}-%{env}-%{region}-uploads", you end up with something truly reusable across any region, environment and product.
I'm pretty sure there's no chance I'd be able to do this with Pulumi.