How to choose a backend for my App?

How would you go about choosing the backend, which stack to run for it, and what are some things I need to consider?

I'm a Front-End Developer, so backend isn't my thing. I've built prototypes in both vue and react (and still can't make up my mind - but that's not what this post is about).

I've tried using firebase but it seems so basic, and not really what I'm looking for (maybe I'm wrong).

Ideally I need to store lots of data, and eventually lots of data will need to be joined (people tell me I should really use sql for this instead of nosql ones).

Types of data:

• Content (such as posts)
• meta data about the posts and meta data about the categories that the content fits into
• user data
• account data (for things like payments or subscription tiers etc)
• user's family data such as children's hobbies / favorite animals or colors or types of films / tv

Heads up, thanks for looking at this!

Have a great day working on your dreams!