So here's my question. To print PDF's is better doing via Backend or Frontend? I've been testing and for me, both have some pros and cons, but I want to listen to u guys.

Backend.
All pdfs will render the same.
Also you don't need to send a pdf library to the client or trust them not to modify the data (if that's important for your usecase).

However, I'm curious to hear cases for rendering on the client.

I always do it backend, why send potentially so much data at the client who can modify it?

But then I deal in multi page (10+) quotes and barcodes so I also have images to load up or create on the fly, not something I would want to kill a browser over.