I'm currently trying to get Lemmy working on Azure Container Apps and Azure Postgres Flexible Server. I've got it all deployed, but I'm having some issues with the reverse proxy.
Regarding the 'best' choice - well it depends on what you mean by 'best'. AKS will be the most flexible and ACI will probably be the simplest (if it will even work for Lemmy - I haven't looked at ACI in years). Container Apps will probably be somewhere in the middle. Container Apps is just an abstraction over Kubernetes, so in theory you should get the scalability and flexibility of k8s without the overhead of managing a cluster.
I got Lemmy up and running on my home Rapberry Pi microk8s cluster pretty easily, so it will work fine on AKS for sure.
I'm looking at Container Apps just as a pet project because I've been waiting for a product like this for years. Kubernetes is awesome, but has always been too complicated for the average software developer to use. It needs a layer of abstraction and that's what Container Apps is. So anyways I figured running Lemmy on it would be a good way to test drive it.
As I said though, I've run into some issues and am almost at the point where I was going to ask for help. If anyone's interested, I can post links to my Github repos with my Terraform code and all that.