New feature announcement – to modal or not to modal

I'm currently designing a way to notify our customers of new features which we've added to our web app. The problem is most of our users don't use our web app, instead they consume our API. Currently we inform our users of new features via email, but the open rate is pretty low.

We've now decided that we should design a notification that will be displayed on the web app. I have two questions. Firstly, out of the two designs, which is the better method to notify users?

1)Standard modal

2)Non-modal notification at the top of the page, which is part of the page but can be dismissed

Secondly, should I surface the notification on the first page the user sees when they sign-in (any page), or should I surface it on the page which includes the new feature? I'm slightly concerned that if I place it on the page that includes the new feature it might get missed. Conversely it makes more sense to show the notification in context with the feature.

I've seen similar questions posed, but I was unable to find any duplicates. Any help would be greatly appreciated.