The eggs are great. For instance I can be up and running building an SDL2 game or make a webserver quickly.

It has good emacs support with geiser-chicken.

Because it compiles down to C the FFI provides a lot of nice ergonomics beyond what I get with Chez Scheme.

Error messages are actually useful with a stacktrace. Can't overstate this.

It supports optional type definitions which reduces the number of tests I need.

The docs are adequate, though I frequently add "MIT scheme" to my search queries. I wasn't able to get chicken-doc setup in NixOS, and the docs website has gone down on me a bunch lately. I wish Chicken had complete documentation available including its eggs in an offline format, like a PDF.