I care about anything. RAM usage, file size, etc. I'm a minimalist when it comes to software. Use as less of all resources as possible. After once writing a router in Python I thought I could do this in Lua, too, but never actually tried. Maybe this would be a nice weekend project?
Even if Nginx is the way to go, I currently experiment with SWS which was suggested here. Technical aspects aside: The software is actively developed and the maintainer provides Docker images on their own (easy for Deploying a container based on that) and a package for my distribution (easy for development testing).
Text-to-speech is now constantly screaming, too!