@doughellmann any of the backends mentioned here, really (or poetry if you're into its opinionated workflow):
https://packaging.python.org/en/latest/tutorials/packaging-projects/#creating-pyproject-toml
It's perhaps important to note that if you're using setuptools, there's nothing wrong with that, you might just need to update how you use it to not use deprecated stuff (unless you actually *want to* be adventurous and try out something new). It's hard to suggest anything specific without knowing what deprecation you're running into.