Some places like to see AWS certs. Doesn't AWS cut a slight rate break based on the number of certified people you have in your org?

I've worked for a couple of companies that get a discount on AWS services if a certain percentage of their employees have AWS certifications.

Which AWS Cert in particular?

Solution Architect Associate is what I'd recommend to start with. Practitioner is for non-technical people, Developer Associate and Sysops Associate are just marginally different than SA, often focusing on services which are marginally useful at best (few people use AWS CI/CD solutions and it makes up most of the difference for developer cert), I wouldn't bother with them. I haven't heard anything about the data engineer one (it seems new).