https://medium.com/@stephane.maarek/an-honest-review-of-aws-..., though this is mainly written pre-GA so I'm not sure how accurate it is now.
I've recently gotten quotes from Confluent Cloud after doing some pricing on AWS for our setup, and they are far more expensive than MSK, but you do get more bells and whistles. It's more cost-effective for us to run our own, which also gives us more flexibility when it comes to monitoring and alerting around the environment.