I honestly really enjoyed Diesel but it's extremely slow migration to async really made it lose traction.
I've used SQLx extensively for projects after that and it was pretty decent.
Other than that the async rust ecosystem is still in a place that makes it literally impossible to provide strong guarantees around handling transactions and make sure that they ended, which is a main reason why diesel-async is not considered stable from my side yet. This problem exists in all other async rust database libraries as well, as it's an language level problem. They just do not document this correctly.
When I started my rust journey Diesel and Rocket were the first few crates I worked with and it really opened up my mind and I haven't turned back since.
As for async, my primary concern for that was to make sure you minimise blocking code calls in your futures. Even if there weren't many performance gains to be made from Diesel itself being async but having database calls marked as Futures could theoretically help the runtime schedule and manage other threads.
I'd like to thank you for you amazing work once more!
That doesn't require an async database library at all. It merely requires some abstraction like [`deadpool-diesel`](https://docs.rs/deadpool-diesel/latest/deadpool_diesel/index...) that ensures that the caller always uses `tokio::spawn_blocking` or similar to run database queries. And yes this scales rather well as the number of database connections in your application is rather low (usually a few ten) and therefore much smaller than the number of threads in the tokio blocking thread-pool.