Notification panel vs banners

When do you normally add notifications to a slide-out panel vs using a banner for it?

By slide-out panel, this is similar to what I mean:

By banner, this is similar to what I mean (but with a dismiss (x) option):

In our app, we have the option to do both.

But I would like to add a notification that I'd really like to get a user's attention on, but at the same time it's also not crucial to their process.

Would it be more appropriate to add it to the slide-out panel? Or would it be better as a (dismissible) banner?