Best WP plugin against attacks?

One of my WP sites got attackt this last couple of days. So i wonder whats the best plugin to use against these attacks? I dont really know what kind of attack it was, but it destroyed my site, and i couldnt even log in to wordpress from it.

There's nothing that will totally prevent it. You could install something like this:
https://wordpress.org/plugins/better-wp-security/

But if I were you, I'd backup my posts, and do a brand new install of WP, and then install the plugin afterwards.

Depends what kind of attack it was, I was going to suggest Cloudfare, but I can't see a DDOS destroying that much. Maybe sign up anyway, if it doesn't work, maybe they found some sort of exploit.

In which case, depending on how valuable your data is, it may be worth hiring a security expert of some sort (some are on the forum) to do some penetration testing or something and help secure your site a bit more. May be something small, could be a complicated thing.

Or if you don't care, you could just hope they don't come back!

Agreed with above, also contact your hosting provider and tell them to dig around and see exactly what happened. Maybe you have a plugin that let someone in and messed around with your database or access to wordpress. Also take a look at your ftp accounts make sure that you have password set even on anonymous login Hope that helps!