I like rocket a lot - practically as easy as writing flask but with glorious type-safety thrown in - but I really wanted async ('like, now') because my project will have a large number of persistent connections. I'm sure rocket will get async eventually but it looks to be some way off.

In comparison to rocket, actix-web does not use codegen tricks so is not as ergonomic or as safe - e.g. it cannot statically check that the path variables that you ask for actually exist on the route - but these are things that a simple test suite easily picks up (incidentally actix-web has a nice built-in test server).

Also I was a little concerned that rocket development has stalled somewhat. 26 PRs waiting at time of writing. As I recall the maintainer is teaching a Rust class as Stanford so he's most likely just very busy.