Membership access or free access and native ads?

Hello everyone!

Lately, I am working on Bootshelf. It's basically a list of around 250 business book titles, tagged with their subjects. This way it's much easier to find a book you are looking for!

As I am finishing the website I was thinking of how to monetize it. The thought I had from the beginning was to add a monthly subscription. But when I was looking for ways to do that, I thought it might be better to make it free and search for people to offer native ads.

I haven't done anything similar before and I have no idea how to do it.

Which way do you think will work better?