Running builds from the repl let’s you skip the startup cost associated with Clojure. It’s faster if you need to run more than build command, or one build command several times.

Lein is easy to get started with, and for simple projects does everything you need. tools.build is endlessly flexible. For some projects, tools.build/tools.deps was much easier for me to use than leiningen (easier to just write clojure code directly than figuring out the whole lein plugin stuff). Use whatever works for you.