I’ll reiterate this for everyone who’s just scrolling to the bottom: there really isn’t a “best” framework or library to use for web apps.
You can write in practically any language for a web app backend at this point without hitch.
It’s really what language your used to and what frameworks you like. I like to write server backends in flexible languages like NodeJS ( or just JS ). Others might prefer more strict languages like Java, C++ or others.
It’s really up to the developer, unless your working for someone and they have preference somehow.